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34 lines
535 B
34 lines
535 B
#include <bits/stdc++.h>
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using namespace std;
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const int N = 110;
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int a[N];
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int n, m;
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int cnt;
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/**
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测试数据：
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5 1
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答案：
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3
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*/
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void dfs(int u, int s1, int s2) {
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//收集答案
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if (u == n + 1) {
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if (s1 - s2 == m) cnt++;
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return;
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}
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//选择了当前的数字
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dfs(u + 1, s1 + a[u], s2);
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//放弃了当前的数字
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dfs(u + 1, s1, s2 + a[u]);
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}
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int main() {
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cin >> n >> m;
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for (int i = 1; i <= n; i++) a[i] = i;
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dfs(1, 0, 0);
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cout << cnt << endl;
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return 0;
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} |