poj 2151

实在没有发现这个题和二分查找或hash有啥关系....

#include <iostream>
#include <string>
#include <vector>
#include <cstdlib>
#include <cmath>
#include <map>
#include <algorithm>
#include <list>
#include <ctime>
#include <set>
#include <string.h>
#include <queue>
#include <cstdio>
using namespace std;
#define CLR(arr, what) memset(arr, what, sizeof(arr))
double pro[1002][32];
double dp[1002][32];
int main() {
    int M, T, N;

    scanf("%d%d%d", &M, &T, &N);
    while (M || T || N) {
        CLR(pro, 0);
        CLR(dp, 0);
        for (int i = 0; i < T; i++) {
            for (int j = 0; j < M; j++) {
                scanf("%lf", &pro[i][j]);
            }
        }
        for (int i = 0; i < T; i++) {
            dp[i][0] = 1 - pro[i][0];
            dp[i][1] = pro[i][0];
            for (int j = 1; j < M; j++) {
                for (int k = j + 1; k >= 0; k--) {
                    switch (k) {
                    case 0:
                        dp[i][k] = dp[i][k] * (1 - pro[i][j]);
                        break;
                    default:
                        dp[i][k] = dp[i][k] * (1 - pro[i][j])
                                + dp[i][k - 1] * (pro[i][j]);
                        break;
                    }
                }
            }
        }
        double p1, p2;
        p1 = 1;
        p2 = 1;
        for (int i = 0; i < T; i++) {
            double t1, t2;
            t1 = 0;
            t2 = 0;
            for (int j = 1; j < N; j++) {
                t1 = t1 + dp[i][j];
            }
            t2=1-dp[i][0];
             p1 = p1 * t1;
            p2 = p2 * t2;
        }
        printf("%.3lf\n", p2 - p1);
        scanf("%d%d%d", &M, &T, &N);
    }
    return 0;
}

from kakamilan