SRM 398(1-250pt)

题意：有两个变量x和y，三种运算符+,*,-，组成等式"变量运算符变量运算符变量运算符变量"，要求每个变量恰好出现两次，且等式的值为val的等式有多少个。注意不计算运算符的优先级，比如2+2*3先计算2+2，最终结果得12。
解法：暴力即可。O(2^4 * 3^3)。终于交到200pt了...
tag:brute-force
  1 // BEGIN CUT HERE
  2 /*
  3  * Author:  plum rain
  4  * score :
  5  */
  6 /*
  7 
  8  */
  9 // END CUT HERE
 10 #line 11 "CountExpressions.cpp"
 11 #include <sstream>
 12 #include <stdexcept>
 13 #include <functional>
 14 #include <iomanip>
 15 #include <numeric>
 16 #include <fstream>
 17 #include <cctype>
 18 #include <iostream>
 19 #include <cstdio>
 20 #include <vector>
 21 #include <cstring>
 22 #include <cmath>
 23 #include <algorithm>
 24 #include <cstdlib>
 25 #include <set>
 26 #include <queue>
 27 #include <bitset>
 28 #include <list>
 29 #include <string>
 30 #include <utility>
 31 #include <map>
 32 #include <ctime>
 33 #include <stack>
 34 
 35 using namespace std;
 36 
 37 #define CLR(x) memset(x, 0, sizeof(x))
 38 #define CLR1(x) memset(x, -1, sizeof(x))
 39 #define PB push_back
 40 #define SZ(v) ((int)(v).size())
 41 #define ALL(t) t.begin(),t.end()
 42 #define zero(x) (((x)>0?(x):-(x))<eps)
 43 #define out(x) cout<<#x<<":"<<(x)<<endl
 44 #define tst(a) cout<<#a<<endl
 45 #define CINBEQUICKER std::ios::sync_with_stdio(false)
 46 
 47 typedef vector<int> VI;
 48 typedef vector<string> VS;
 49 typedef vector<double> VD;
 50 typedef pair<int, int> pii;
 51 typedef long long int64;
 52 
 53 const double eps = 1e-8;
 54 const double PI = atan(1.0)*4;
 55 const int maxint = 2139062143;
 56 
 57 int num(int x)
 58 {
 59     int ret = 0;
 60     while (x){
 61         if (x & 1) ++ ret;
 62         x >>= 1;
 63     }
 64     return ret;
 65 }
 66 
 67 int gao(int s, int t, int x, int y)
 68 {
 69     int num = s & 1 ? x : y, times = 0;
 70     s >>= 1;
 71     while (times < 3){
 72         int tmp = s & 1 ? x : y;
 73         int suan = t % 3;
 74         if (suan == 0) num = tmp + num;
 75         else if (suan == 1) num = tmp * num;
 76         else num = num - tmp;
 77 
 78         s >>= 1; t /= 3;
 79         ++ times; 
 80     }
 81     return num;
 82 }
 83 
 84 class CountExpressions
 85 {
 86     public:
 87         int calcExpressions(int x, int y, int val){
 88             int cnt = 0;
 89             int the = 3 * 3 * 3;
 90             for (int i = 0; i < (1<<4); ++ i) if (num(i) == 2)
 91                 for (int j = 0; j < the; ++ j)
 92                     if (gao(i, j, x, y) == val) ++ cnt;
 93             return cnt;
 94         }
 95         
 96 // BEGIN CUT HERE
 97     public:
 98     void run_test(int Case) { if ((Case == -1) || (Case == 0)) test_case_0(); if ((Case == -1) || (Case == 1)) test_case_1(); if ((Case == -1) || (Case == 2)) test_case_2(); if ((Case == -1) || (Case == 3)) test_case_3(); if ((Case == -1) || (Case == 4)) test_case_4(); if ((Case == -1) || (Case == 5)) test_case_5(); }
 99     private:
100     template <typename T> string print_array(const vector<T> &V) { ostringstream os; os << "{ "; for (typename vector<T>::const_iterator iter = V.begin(); iter != V.end(); ++iter) os << '"' << *iter << "","; os << " }"; return os.str(); }
101     void verify_case(int Case, const int &Expected, const int &Received) { cerr << "Test Case #" << Case << "..."; if (Expected == Received) cerr << "PASSED" << endl; else { cerr << "FAILED" << endl; cerr << "	Expected: "" << Expected << '"' << endl; cerr << "	Received: "" << Received << '"' << endl; } }
102     void test_case_0() { int Arg0 = 7; int Arg1 = 8; int Arg2 = 16; int Arg3 = 9; verify_case(0, Arg3, calcExpressions(Arg0, Arg1, Arg2)); }
103     void test_case_1() { int Arg0 = 3; int Arg1 = 5; int Arg2 = 7; int Arg3 = 5; verify_case(1, Arg3, calcExpressions(Arg0, Arg1, Arg2)); }
104     void test_case_2() { int Arg0 = 99; int Arg1 = 100; int Arg2 = 98010000; int Arg3 = 6; verify_case(2, Arg3, calcExpressions(Arg0, Arg1, Arg2)); }
105     void test_case_3() { int Arg0 = -99; int Arg1 = 42; int Arg2 = -1764; int Arg3 = 2; verify_case(3, Arg3, calcExpressions(Arg0, Arg1, Arg2)); }
106     void test_case_4() { int Arg0 = 100; int Arg1 = -100; int Arg2 = -100000000; int Arg3 = 0; verify_case(4, Arg3, calcExpressions(Arg0, Arg1, Arg2)); }
107     void test_case_5() { int Arg0 = 1; int Arg1 = 2; int Arg2 = 5; int Arg3 = 17; verify_case(5, Arg3, calcExpressions(Arg0, Arg1, Arg2)); }
108 
109 // END CUT HERE
110 
111 };
112 
113 // BEGIN CUT HERE
114 int main()
115 {
116 //    freopen( "a.out" , "w" , stdout );    
117     CountExpressions ___test;
118     ___test.run_test(-1);
119        return 0;
120 }
121 // END CUT HERE
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