zzulioj - 2617 体检

题目链接：http://acm.zzuli.edu.cn/problem.php?id=2617

　　这个题本来想着靠排序过的，结果思来想去死活过不了只好用全排列暴力过了，关于全排列算法请自行百度，这里不再赘述（其实我也是现学的）。

#include<set>
#include<map>
#include<stack>
#include<queue>
#include<cmath>
#include<cstdio>
#include<cctype>
#include<string>
#include<vector>
#include<climits>
#include<cstring>
#include<cstdlib>
#include<iostream>
#include<algorithm>
#define max(a, b) (a > b ? a : b)
#define min(a, b) (a < b ? a : b)
#define mst(a) memset(a, 0, sizeof(a))
#define _test printf("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n")
using namespace std;
typedef long long ll;
typedef pair<int, int> P;
const double eps = 1e-7;
const int INF = 0x3f3f3f3f;
const ll ll_INF = 233333333333333;
const int maxn = 1e4+10;
struct test {
    ll a, b;
}num[10], temp[10];
ll res[maxn];
int kase;
void solve(int start, int n) {
    if (start == n) {
        ll sum = 0;
        //_test;
        for (int i = 0; i<n; ++i) { //求结果
            //printf("%lld %lld\n", num[i].a, num[i].b);
            sum += (num[i].b * sum + num[i].a);
        }
        res[kase++] = sum;
    }
    for (int i = start; i<n; ++i) { //求全排列
        swap(num[start], num[i]); //交换
        solve(start+1, n);
        swap(num[i], num[start]); //复位
    }
}
int main(void) {
    int t;
    scanf("%d", &t);
    while(t--) {
        kase = 0;
        fill(res, res+maxn, ll_INF); //将储存答案的数组元素全部初始化为一个足够大的值，方便下面直接调用函数求最小值
        int n;
        scanf("%d", &n);
        for (int i = 0; i<n; ++i)
            scanf("%lld%lld", &num[i].a, &num[i].b);
        solve(0, n); //计算出所有排列的可能结果
        printf("%lld\n", *min_element(res, res+maxn));
    }
    return 0;
}