HDU5802-windows 10-dfs+贪心

音量减的时候，分两种，一种是减到大于目标Ｍ，另一种是减到小于Ｍ，停顿的时候可以减少最后往上加的次数，小于０的时候变成０

然后比一下这两种的最小值。

 1 /*--------------------------------------------------------------------------------------*/
 2 #include <algorithm>
 3 #include <iostream>
 4 #include <cstring>
 5 #include <ctype.h>
 6 #include <cstdlib>
 7 #include <cstdio>
 8 #include <vector>
 9 #include <string>
10 #include <queue>
11 #include <stack>
12 #include <cmath>
13 #include <set>
14 #include <map>
15 
16 //debug function for a N*M array
17 #define debug_map(N,M,G) printf("
");for(int i=0;i<(N);i++)
18 {for(int j=0;j<(M);j++){
19 printf("%d",G[i][j]);}printf("
");}
20 //debug function for int,float,double,etc.
21 #define debug_var(X) cout<<#X"="<<X<<endl;
22 #define LL long long
23 const int INF = 0x3f3f3f3f;
24 const int LLINF = 0x3f3f3f3f3f3f3f3f;
25 /*--------------------------------------------------------------------------------------*/
26 using namespace std;
27 
28 LL N,M,ans;
29 int T;
30 
31 LL sum(int x) {return (1LL<<x) - 1LL;}
32 
33 LL dfs(LL cur,LL cnt,int stop)
34 {
35     //printf("cur:%d cnt:%d
",cur,cnt);
36     if(cur == M) return cnt;
37     int i = 0;
38     while(cur-sum(i) > M) i++;
39 
40     if(cur -sum(i) == M ) return cnt + i;
41     LL up =  M - max(0LL,cur-sum(i) );
42     LL res = i + max(0LL,up-stop);
43     return min(cnt+res , dfs(cur-sum(i-1) , cnt + i,stop+1));
44 }
45 
46 int main()
47 {
48     scanf("%d",&T);
49     while(T--)
50     {
51         ans = LLINF;
52         scanf("%I64d%I64d",&N,&M);
53         if(N <= M)
54         {
55             printf("%I64d
",M-N);
56             continue;
57         }
58 
59         printf("%I64d
",dfs(N,0,0));
60     }
61 }