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9.2.cpp
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9.2.cpp
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/*
* 题目名称:神奇的口袋
* 题目来源:北京大学复试上机题
* 题目链接:http://t.cn/Ai0u0GUz
* 代码作者:杨泽邦(炉灰)
*/
#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
const int MAXN = 25;
int arr[MAXN];
bool visit[MAXN];
void DFS(int index, int sum, int n, int& answer) {
if (sum == 40) {
answer++;
return;
}
for (int i = index; i < n; ++i) {
if (visit[i] || sum + arr[i] > 40) {
continue;
}
visit[i] = true;
DFS(i + 1, sum + arr[i], n, answer);
visit[i] = false;
}
return ;
}
int main() {
int n;
while(scanf("%d", &n) != EOF) {
for (int i = 0; i < n; ++i) {
scanf("%d", &arr[i]);
}
memset(visit, false, sizeof(visit));
int answer = 0;
DFS(0, 0, n, answer);
printf("%d\n", answer);
}
return 0;
}