拔河比赛【DFS】

>Link

ybtoj拔河比赛

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>解题思路

一道非常典型的DFS，通过维护人数不超过总人数的一半来剪枝
为了方便，我DFS的时候用一个变量c来记录两队体重之差，左边队的就+，右边队的就-，最后取c的绝对值

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>代码

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#define N 30
#define inf 1 << 30
using namespace std;

int T, n, w[N], ans;

void dfs (int now, int cnt1, int cnt2, int c)
{
    
    
	if (now == n + 1)
	{
    
    
		ans = min (ans, abs (c));
		return;
	}
	if (cnt1 < n / 2 + (n & 1))
	  dfs (now + 1, cnt1 + 1, cnt2, c + w[now]);
	if (cnt2 < n / 2 + (n & 1))
	  dfs (now + 1, cnt1, cnt2 + 1, c - w[now]);
}
void work ()
{
    
    
	scanf ("%d", &n);
	for (int i = 1; i <= n; i++) scanf ("%d", &w[i]);
	ans = inf;
	dfs (1, 0, 0, 0);
	printf ("%d\n", ans);
}

int main()
{
    
    
	scanf ("%d", &T);
	while (T--) work ();
	return 0;
}