Manthan, Codefest 16 E. Startup Funding ST表二分数学

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</head> <body class='typora-export' > <div id='write' class = 'is-node'><h1><a name='header-n321' class='md-header-anchor '></a><center>E. Startup Funding</center></h1><h2><a name='header-n323' class='md-header-anchor '></a>题目连接：</h2><a href='http://codeforces.com/contest/633/problem/E' target='_blank' class='url'>http://codeforces.com/contest/633/problem/E</a><h2><a name='header-n325' class='md-header-anchor '></a>Description</h2>An e-commerce startup pitches to the investors to get funding. They have been functional for n weeks now and also have a website!For each week they know the number of unique visitors during this week vi and the revenue ci. To evaluate the potential of the startup at some range of weeks from l to r inclusive investors use the minimum among the maximum number of visitors multiplied by 100 and the minimum revenue during this period, that is:The truth is that investors have no idea how to efficiently evaluate the startup, so they are going to pick some k random distinct weeks li and give them to managers of the startup. For each li they should pick some ri ≥ li and report maximum number of visitors and minimum revenue during this period.Then, investors will calculate the potential of the startup for each of these ranges and take minimum value of p(li, ri) as the total evaluation grade of the startup. Assuming that managers of the startup always report the optimal values of ri for some particular li, i.e., the value such that the resulting grade of the startup is maximized, what is the expected resulting grade of the startup?<h2><a name='header-n330' class='md-header-anchor '></a>Input</h2>The first line of the input contains two integers n and k (1 ≤ k ≤ n ≤ 1 000 000).The second line contains n integers vi (<svg xmlns:xlink="http://www.w3.org/1999/xlink" width="18.344ex" height="2.884ex" viewBox="0 -970.7 7898.2 1241.8" role="img" focusable="false" style="vertical-align: -0.63ex;"><defs><path stroke-width="0" id="E1178-MJMATHI-6C" d="M117 59Q117 26 142 26Q179 26 205 131Q211 151 215 152Q217 153 225 153H229Q238 153 241 153T246 151T248 144Q247 138 245 128T234 90T214 43T183 6T137 -11Q101 -11 70 11T38 85Q38 97 39 102L104 360Q167 615 167 623Q167 626 166 628T162 632T157 634T149 635T141 636T132 637T122 637Q112 637 109 637T101 638T95 641T94 647Q94 649 96 661Q101 680 107 682T179 688Q194 689 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405Q286 405 239 331Q229 315 224 298T190 165Q156 25 151 16Q138 -11 108 -11Q95 -11 87 -5T76 7T74 17Q74 30 114 189T154 366Q154 405 128 405Q107 405 92 377T68 316T57 280Q55 278 41 278H27Q21 284 21 287Z"></path><path stroke-width="0" id="E1178-MJMATHI-67" d="M311 43Q296 30 267 15T206 0Q143 0 105 45T66 160Q66 265 143 353T314 442Q361 442 401 394L404 398Q406 401 409 404T418 412T431 419T447 422Q461 422 470 413T480 394Q480 379 423 152T363 -80Q345 -134 286 -169T151 -205Q10 -205 10 -137Q10 -111 28 -91T74 -71Q89 -71 102 -80T116 -111Q116 -121 114 -130T107 -144T99 -154T92 -162L90 -164H91Q101 -167 151 -167Q189 -167 211 -155Q234 -144 254 -122T282 -75Q288 -56 298 -13Q311 35 311 43ZM384 328L380 339Q377 350 375 354T369 368T359 382T346 393T328 402T306 405Q262 405 221 352Q191 313 171 233T151 117Q151 38 213 38Q269 38 323 108L331 118L384 328Z"></path><path stroke-width="0" id="E1178-MJMATHI-65" d="M39 168Q39 225 58 272T107 350T174 402T244 433T307 442H310Q355 442 388 420T421 355Q421 265 310 237Q261 224 176 223Q139 223 138 221Q138 219 132 186T125 128Q125 81 146 54T209 26T302 45T394 111Q403 121 406 121Q410 121 419 112T429 98T420 82T390 55T344 24T281 -1T205 -11Q126 -11 83 42T39 168ZM373 353Q367 405 305 405Q272 405 244 391T199 357T170 316T154 280T149 261Q149 260 169 260Q282 260 327 284T373 353Z"></path><path stroke-width="0" id="E1178-MJMAIN-31" d="M213 578L200 573Q186 568 160 563T102 556H83V602H102Q149 604 189 617T245 641T273 663Q275 666 285 666Q294 666 302 660V361L303 61Q310 54 315 52T339 48T401 46H427V0H416Q395 3 257 3Q121 3 100 0H88V46H114Q136 46 152 46T177 47T193 50T201 52T207 57T213 61V578Z"></path><path stroke-width="0" id="E1178-MJMAIN-2264" d="M674 636Q682 636 688 630T694 615T687 601Q686 600 417 472L151 346L399 228Q687 92 691 87Q694 81 694 76Q694 58 676 56H670L382 192Q92 329 90 331Q83 336 83 348Q84 359 96 365Q104 369 382 500T665 634Q669 636 674 636ZM84 -118Q84 -108 99 -98H678Q694 -104 694 -118Q694 -130 679 -138H98Q84 -131 84 -118Z"></path><path stroke-width="0" id="E1178-MJMATHI-76" 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287Q60 286 59 284T58 281T56 279T53 278T49 278T41 278H27Q21 284 21 287Z"></path><path stroke-width="0" id="E1178-MJMAIN-30" d="M96 585Q152 666 249 666Q297 666 345 640T423 548Q460 465 460 320Q460 165 417 83Q397 41 362 16T301 -15T250 -22Q224 -22 198 -16T137 16T82 83Q39 165 39 320Q39 494 96 585ZM321 597Q291 629 250 629Q208 629 178 597Q153 571 145 525T137 333Q137 175 145 125T181 46Q209 16 250 16Q290 16 318 46Q347 76 354 130T362 333Q362 478 354 524T321 597Z"></path><path stroke-width="0" id="E1178-MJMAIN-37" d="M55 458Q56 460 72 567L88 674Q88 676 108 676H128V672Q128 662 143 655T195 646T364 644H485V605L417 512Q408 500 387 472T360 435T339 403T319 367T305 330T292 284T284 230T278 162T275 80Q275 66 275 52T274 28V19Q270 2 255 -10T221 -22Q210 -22 200 -19T179 0T168 40Q168 198 265 368Q285 400 349 489L395 552H302Q128 552 119 546Q113 543 108 522T98 479L95 458V455H55V458Z"></path></defs><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="matrix(1 0 0 -1 0 0)"><use xlink:href="#E1178-MJMATHI-6C" x="0" y="0"></use><use xlink:href="#E1178-MJMATHI-61" x="298" y="0"></use><use xlink:href="#E1178-MJMATHI-72" x="827" y="0"></use><use xlink:href="#E1178-MJMATHI-67" x="1278" y="0"></use><use xlink:href="#E1178-MJMATHI-65" x="1758" y="0"></use><use xlink:href="#E1178-MJMAIN-31" x="2224" y="0"></use><use xlink:href="#E1178-MJMAIN-2264" x="3057" y="0"></use><use xlink:href="#E1178-MJMATHI-76" x="4169" y="0"></use><use xlink:href="#E1178-MJMATHI-69" x="4654" y="0"></use><use xlink:href="#E1178-MJMAIN-2264" x="5333" y="0"></use><g transform="translate(6444,0)"><use xlink:href="#E1178-MJMAIN-31"></use><use xlink:href="#E1178-MJMAIN-30" x="500" y="0"></use><use transform="scale(0.707)" xlink:href="#E1178-MJMAIN-37" x="1414" y="555"></use></g></g></svg><script type="math/tex">large1 ≤ vi ≤ 10^7</script>) — the number of unique visitors during each week.The third line contains n integers ci (<svg xmlns:xlink="http://www.w3.org/1999/xlink" width="13.058ex" height="2.759ex" viewBox="0 -970.7 5622.2 1188" role="img" focusable="false" style="vertical-align: -0.505ex;"><defs><path stroke-width="0" id="E1160-MJMAIN-31" d="M213 578L200 573Q186 568 160 563T102 556H83V602H102Q149 604 189 617T245 641T273 663Q275 666 285 666Q294 666 302 660V361L303 61Q310 54 315 52T339 48T401 46H427V0H416Q395 3 257 3Q121 3 100 0H88V46H114Q136 46 152 46T177 47T193 50T201 52T207 57T213 61V578Z"></path><path stroke-width="0" id="E1160-MJMAIN-2264" d="M674 636Q682 636 688 630T694 615T687 601Q686 600 417 472L151 346L399 228Q687 92 691 87Q694 81 694 76Q694 58 676 56H670L382 192Q92 329 90 331Q83 336 83 348Q84 359 96 365Q104 369 382 500T665 634Q669 636 674 636ZM84 -118Q84 -108 99 -98H678Q694 -104 694 -118Q694 -130 679 -138H98Q84 -131 84 -118Z"></path><path stroke-width="0" id="E1160-MJMATHI-63" d="M34 159Q34 268 120 355T306 442Q362 442 394 418T427 355Q427 326 408 306T360 285Q341 285 330 295T319 325T330 359T352 380T366 386H367Q367 388 361 392T340 400T306 404Q276 404 249 390Q228 381 206 359Q162 315 142 235T121 119Q121 73 147 50Q169 26 205 26H209Q321 26 394 111Q403 121 406 121Q410 121 419 112T429 98T420 83T391 55T346 25T282 0T202 -11Q127 -11 81 37T34 159Z"></path><path stroke-width="0" id="E1160-MJMATHI-69" d="M184 600Q184 624 203 642T247 661Q265 661 277 649T290 619Q290 596 270 577T226 557Q211 557 198 567T184 600ZM21 287Q21 295 30 318T54 369T98 420T158 442Q197 442 223 419T250 357Q250 340 236 301T196 196T154 83Q149 61 149 51Q149 26 166 26Q175 26 185 29T208 43T235 78T260 137Q263 149 265 151T282 153Q302 153 302 143Q302 135 293 112T268 61T223 11T161 -11Q129 -11 102 10T74 74Q74 91 79 106T122 220Q160 321 166 341T173 380Q173 404 156 404H154Q124 404 99 371T61 287Q60 286 59 284T58 281T56 279T53 278T49 278T41 278H27Q21 284 21 287Z"></path><path stroke-width="0" id="E1160-MJMAIN-30" d="M96 585Q152 666 249 666Q297 666 345 640T423 548Q460 465 460 320Q460 165 417 83Q397 41 362 16T301 -15T250 -22Q224 -22 198 -16T137 16T82 83Q39 165 39 320Q39 494 96 585ZM321 597Q291 629 250 629Q208 629 178 597Q153 571 145 525T137 333Q137 175 145 125T181 46Q209 16 250 16Q290 16 318 46Q347 76 354 130T362 333Q362 478 354 524T321 597Z"></path><path stroke-width="0" id="E1160-MJMAIN-37" d="M55 458Q56 460 72 567L88 674Q88 676 108 676H128V672Q128 662 143 655T195 646T364 644H485V605L417 512Q408 500 387 472T360 435T339 403T319 367T305 330T292 284T284 230T278 162T275 80Q275 66 275 52T274 28V19Q270 2 255 -10T221 -22Q210 -22 200 -19T179 0T168 40Q168 198 265 368Q285 400 349 489L395 552H302Q128 552 119 546Q113 543 108 522T98 479L95 458V455H55V458Z"></path></defs><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="matrix(1 0 0 -1 0 0)"><use xlink:href="#E1160-MJMAIN-31" x="0" y="0"></use><use xlink:href="#E1160-MJMAIN-2264" x="833" y="0"></use><use xlink:href="#E1160-MJMATHI-63" x="1945" y="0"></use><use xlink:href="#E1160-MJMATHI-69" x="2378" y="0"></use><use xlink:href="#E1160-MJMAIN-2264" x="3056" y="0"></use><g transform="translate(4168,0)"><use xlink:href="#E1160-MJMAIN-31"></use><use xlink:href="#E1160-MJMAIN-30" x="500" y="0"></use><use transform="scale(0.707)" xlink:href="#E1160-MJMAIN-37" x="1414" y="555"></use></g></g></svg><script type="math/tex">1 ≤ ci ≤ 10^7</script>) —the revenue for each week.<h2><a name='header-n334' class='md-header-anchor '></a>Output</h2>Print a single real value — the expected grade of the startup. Your answer will be considered correct if its absolute or relative error does not exceed <svg xmlns:xlink="http://www.w3.org/1999/xlink" width="4.654ex" height="2.509ex" viewBox="0 -970.7 2003.7 1080.4" role="img" focusable="false" style="vertical-align: -0.255ex;"><defs><path stroke-width="0" id="E1197-MJMAIN-31" d="M213 578L200 573Q186 568 160 563T102 556H83V602H102Q149 604 189 617T245 641T273 663Q275 666 285 666Q294 666 302 660V361L303 61Q310 54 315 52T339 48T401 46H427V0H416Q395 3 257 3Q121 3 100 0H88V46H114Q136 46 152 46T177 47T193 50T201 52T207 57T213 61V578Z"></path><path stroke-width="0" id="E1197-MJMAIN-30" d="M96 585Q152 666 249 666Q297 666 345 640T423 548Q460 465 460 320Q460 165 417 83Q397 41 362 16T301 -15T250 -22Q224 -22 198 -16T137 16T82 83Q39 165 39 320Q39 494 96 585ZM321 597Q291 629 250 629Q208 629 178 597Q153 571 145 525T137 333Q137 175 145 125T181 46Q209 16 250 16Q290 16 318 46Q347 76 354 130T362 333Q362 478 354 524T321 597Z"></path><path stroke-width="0" id="E1197-MJMAIN-2212" d="M84 237T84 250T98 270H679Q694 262 694 250T679 230H98Q84 237 84 250Z"></path><path stroke-width="0" id="E1197-MJMAIN-36" d="M42 313Q42 476 123 571T303 666Q372 666 402 630T432 550Q432 525 418 510T379 495Q356 495 341 509T326 548Q326 592 373 601Q351 623 311 626Q240 626 194 566Q147 500 147 364L148 360Q153 366 156 373Q197 433 263 433H267Q313 433 348 414Q372 400 396 374T435 317Q456 268 456 210V192Q456 169 451 149Q440 90 387 34T253 -22Q225 -22 199 -14T143 16T92 75T56 172T42 313ZM257 397Q227 397 205 380T171 335T154 278T148 216Q148 133 160 97T198 39Q222 21 251 21Q302 21 329 59Q342 77 347 104T352 209Q352 289 347 316T329 361Q302 397 257 397Z"></path></defs><g stroke="currentColor" fill="currentColor" stroke-width="0" transform="matrix(1 0 0 -1 0 0)"><use xlink:href="#E1197-MJMAIN-31"></use><use xlink:href="#E1197-MJMAIN-30" x="500" y="0"></use><g transform="translate(1000,392)"><use transform="scale(0.707)" xlink:href="#E1197-MJMAIN-2212" x="0" y="0"></use><use transform="scale(0.707)" xlink:href="#E1197-MJMAIN-36" x="778" y="0"></use></g></g></svg><script type="math/tex">10^{-6}</script>.Namely: let's assume that your answer is a, and the answer of the jury is b. The checker program will consider your answer correct, if .<h2><a name='header-n337' class='md-header-anchor '></a>Sample Input</h2>3 2 3 2 1 300 200 300<h2><a name='header-n339' class='md-header-anchor '></a>Sample Output</h2>133.3333333<h2><a name='header-n341' class='md-header-anchor '></a>Hint</h2><h2><a name='header-n342' class='md-header-anchor '></a>题意</h2>有n个人，每个人有两个权值，v[i]和c[i]然后有一个函数p(l,r) = min(100*max(v[l..r]),min(c[l..r]))对于每一个i，你需要找到一个最大的p(i,ri)然后现在从n个p(i,ri)中选取k个，然后再从这k个中选取其中最小的问你选出来的数的期望是多少<h2><a name='header-n348' class='md-header-anchor '></a>题解：</h2>这个题目很明显分成了两个部分：１．求val[i] (即最大p(i,ri))２．求期望<h3><a name='header-n352' class='md-header-anchor '></a>step1:</h3>我们先来讨论第一个问题，对于位置i,<svg xmlns:xlink="http://www.w3.org/1999/xlink" width="40.97ex" height="12.634ex" viewBox="0 -1186 17639.9 5439.7" role="img" focusable="false" style="vertical-align: -9.88ex;"><defs><path stroke-width="0" id="E1145-MJMATHI-66" d="M118 -162Q120 -162 124 -164T135 -167T147 -168Q160 -168 171 -155T187 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class='md-header-anchor '></a>step2:</h3>这个就是一个组合数学的问题，只要有一点基础都可以推出来（因为连我都推出来了）先将val从小到大排序，答案就是<svg xmlns:xlink="http://www.w3.org/1999/xlink" width="30.617ex" height="9.884ex" viewBox="0 -2746.8 13182.1 4255.7" role="img" focusable="false" style="vertical-align: -3.505ex;"><defs><path stroke-width="0" id="E1149-MJSZ1-2211" d="M61 748Q64 750 489 750H913L954 640Q965 609 976 579T993 533T999 516H979L959 517Q936 579 886 621T777 682Q724 700 655 705T436 710H319Q183 710 183 709Q186 706 348 484T511 259Q517 250 513 244L490 216Q466 188 420 134T330 27L149 -187Q149 -188 362 -188Q388 -188 436 -188T506 -189Q679 -189 778 -162T936 -43Q946 -27 959 6H999L913 -249L489 -250Q65 -250 62 -248Q56 -246 56 -239Q56 -234 118 -161Q186 -81 245 -11L428 206Q428 207 242 462L57 717L56 728Q56 744 61 748Z"></path><path stroke-width="0" id="E1149-MJMATHI-6E" d="M21 287Q22 293 24 303T36 341T56 388T89 425T135 442Q171 442 195 424T225 390T231 369Q231 367 232 367L243 378Q304 442 382 442Q436 442 469 415T503 336T465 179T427 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x="9255" y="0"></use><use transform="scale(1.44)" xlink:href="#E1151-MJMAIN-31" x="10256" y="0"></use><use transform="scale(1.44)" xlink:href="#E1151-MJMAIN-29" x="10756" y="0"></use></g></svg><script type="math/tex">Large F(i)=frac{n-k-i+2}{n-i+1}*F(i-1)</script>这样我们就做完啦。<h2><a name='header-n362' class='md-header-anchor '></a>代码</h2><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="c++" style="break-inside: unset;"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="c++"><div style="overflow: hidden; position: relative; 3px; height: 0px; top: 0px; left: 4px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right- 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre>xxxxxxxxxx</pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation" style=""><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; 0px;"></div><pre class=" CodeMirror-line " role="presentation">#include<bits/stdc++.h></pre></div><pre class=" CodeMirror-line " role="presentation">using namespace std;</pre><pre class=" CodeMirror-line " role="presentation">#define ll long long</pre><pre class=" CodeMirror-line " role="presentation">#define N 1000050</pre><pre class=" CodeMirror-line " role="presentation">int n,k,a[N],b[N],val[N],mx[N][21],mi[N][21],mm[N];</pre><pre class=" CodeMirror-line " role="presentation">template<typename T>void read(T&x)</pre><pre class=" CodeMirror-line " role="presentation">{</pre><pre class=" CodeMirror-line " role="presentation">    ll k=0; char c=getchar();</pre><pre class=" CodeMirror-line " role="presentation">    x=0;</pre><pre class=" CodeMirror-line " role="presentation">    while(!isdigit(c)&&c!=EOF)k^=c=='-',c=getchar();</pre><pre class=" CodeMirror-line " role="presentation">    if (c==EOF)exit(0);</pre><pre class=" CodeMirror-line " role="presentation">    while(isdigit(c))x=x*10+c-'0',c=getchar();</pre><pre class=" CodeMirror-line " role="presentation">    x=k?-x:x;</pre><pre class=" CodeMirror-line " role="presentation">}</pre><pre class=" CodeMirror-line " role="presentation">void read_char(char &c)</pre><pre class=" CodeMirror-line " role="presentation">{while(!isalpha(c=getchar())&&c!=EOF);}</pre><pre class=" CodeMirror-line " role="presentation">void init_ST(int n)</pre><pre class=" CodeMirror-line " role="presentation">{</pre><pre class=" CodeMirror-line " role="presentation">    mm[0]=-1;</pre><pre class=" CodeMirror-line " role="presentation">    for(int i=1;i<=n;i++)</pre><pre class=" CodeMirror-line " role="presentation">   {</pre><pre class=" CodeMirror-line " role="presentation">        mx[i][0]=a[i];</pre><pre class=" CodeMirror-line " role="presentation">        mi[i][0]=b[i];</pre><pre class=" CodeMirror-line " role="presentation">        mm[i]=(i&(i-1))==0?mm[i-1]+1:mm[i-1];</pre><pre class=" CodeMirror-line " role="presentation">   }</pre><pre class=" CodeMirror-line " role="presentation">    for(int i=1;i<=20;i++)</pre><pre class=" CodeMirror-line " role="presentation">        for(int j=1;j+(1<<i)-1<=n;j++)</pre><pre class=" CodeMirror-line " role="presentation">       {</pre><pre class=" CodeMirror-line " role="presentation">            mx[j][i]=max(mx[j][i-1],mx[j+(1<<(i-1))][i-1]);</pre><pre class=" CodeMirror-line " role="presentation">            mi[j][i]=min(mi[j][i-1],mi[j+(1<<(i-1))][i-1]);</pre><pre class=" CodeMirror-line " role="presentation">       }</pre><pre class=" CodeMirror-line " role="presentation">}</pre><pre class=" CodeMirror-line " role="presentation">int compare(int x,int y)</pre><pre class=" CodeMirror-line " role="presentation">{</pre><pre class=" CodeMirror-line " role="presentation">    if (x>y)swap(x,y);</pre><pre class=" CodeMirror-line " role="presentation">    int k=mm[y-x+1],a1,a2;</pre><pre class=" CodeMirror-line " role="presentation">    a1=max(mx[x][k],mx[y-(1<<k)+1][k]);</pre><pre class=" CodeMirror-line " role="presentation">    a2=min(mi[x][k],mi[y-(1<<k)+1][k]);</pre><pre class=" CodeMirror-line " role="presentation">    return a1-a2;</pre><pre class=" CodeMirror-line " role="presentation">}</pre><pre class=" CodeMirror-line " role="presentation">int get_p(int x,int y)</pre><pre class=" CodeMirror-line " role="presentation">{</pre><pre class=" CodeMirror-line " role="presentation">    if (y>n)return 0;</pre><pre class=" CodeMirror-line " role="presentation">    if (x>y)swap(x,y);</pre><pre class=" CodeMirror-line " role="presentation">    int k=mm[y-x+1],a1,a2;</pre><pre class=" CodeMirror-line " role="presentation">    a1=max(mx[x][k],mx[y-(1<<k)+1][k]);</pre><pre class=" CodeMirror-line " role="presentation">    a2=min(mi[x][k],mi[y-(1<<k)+1][k]);</pre><pre class=" CodeMirror-line " role="presentation">    return min(a1,a2);</pre><pre class=" CodeMirror-line " role="presentation">}</pre><pre class=" CodeMirror-line " role="presentation">int main()</pre><pre class=" CodeMirror-line " role="presentation">{</pre><pre class=" CodeMirror-line " role="presentation">#ifndef ONLINE_JUDGE</pre><pre class=" CodeMirror-line " role="presentation">    freopen("aa.in","r",stdin);</pre><pre class=" CodeMirror-line " role="presentation">#endif</pre><pre class=" CodeMirror-line " role="presentation">    read(n); read(k);</pre><pre class=" CodeMirror-line " role="presentation">    for(int i=1;i<=n;i++)read(a[i]),a[i]*=100;</pre><pre class=" CodeMirror-line " role="presentation">    for(int i=1;i<=n;i++)read(b[i]);</pre><pre class=" CodeMirror-line " role="presentation">    init_ST(n);</pre><pre class=" CodeMirror-line " role="presentation">    int r=0;</pre><pre class=" CodeMirror-line " role="presentation">    for(int i=1;i<=n;i++)</pre><pre class=" CodeMirror-line " role="presentation">   {</pre><pre class=" CodeMirror-line " role="presentation">        r=max(r,i);</pre><pre class=" CodeMirror-line " role="presentation">        while(r+1<=n&&compare(i,r+1)<=0)r++;</pre><pre class=" CodeMirror-line " role="presentation">        val[i]=max(get_p(i,r),get_p(i,r+1));</pre><pre class=" CodeMirror-line " role="presentation">   }</pre><pre class=" CodeMirror-line " role="presentation">    sort(val+1,val+n+1);</pre><pre class=" CodeMirror-line " role="presentation">    double ans=0,f2,f1=k*1.0/(n-k+1);</pre><pre class=" CodeMirror-line " role="presentation">    for(int i=1;i<=n;i++)</pre><pre class=" CodeMirror-line " role="presentation">       {</pre><pre class=" CodeMirror-line " role="presentation">            f2=f1*(n-k-i+2)*1.0/(n-i+1);</pre><pre class=" CodeMirror-line " role="presentation">            ans+=f2*val[i];</pre><pre class=" CodeMirror-line " role="presentation">            f1=f2;</pre><pre class=" CodeMirror-line " role="presentation">       }</pre><pre class=" CodeMirror-line " role="presentation">    printf("%.7lf",ans);</pre><pre class=" CodeMirror-line " role="presentation">}</pre></div></div></div></div></div><div style="position: absolute; height: 0px; 1px; border-bottom: 0px solid transparent; top: 1800px;"></div><div class="CodeMirror-gutters" style="display: none; height: 1800px;"></div></div></div></pre> </div> </body>

Manthan, Codefest 16 E. Startup Funding ST表二分数学

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Manthan, Codefest 16 E. Startup Funding ST表 二分 数学

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Manthan, Codefest 16 E. Startup Funding ST表二分数学