poj 1011 Sticks-优快云博客

本文链接：https://blog.youkuaiyun.com/Fawkess/article/details/102662219

本文深入探讨了深度优先搜索（DFS）算法结合剪枝技术在解决特定问题中的应用。通过实例详细介绍了如何利用DFS进行搜索，并通过剪枝策略提高算法效率，避免不必要的计算，从而在复杂问题中找到最优解。

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这道题是个dfs加剪枝，不剪枝过不了

#include <iostream>
#include <cstdio>
#include <iomanip>
#include <string>
#include <cstdlib>
#include <cstring>
#include <queue>
#include <set>
#include <vector>
#include <map>
#include <algorithm>
#include <cmath>

#define INF 0x3f3f3f3f
#define LINF 0x3f3f3f3f3f3f3f3f
#define ll long long
#define ull unsigned long long
#define uint unsigned int
#define l(x) x<<1
#define r(x) x<<1|1
#define ms(a,b) memset(a,b,sizeof(a))


using namespace std;

int n;
int stick[100];
int sum;
int vis[100];
int len;

bool cmp(const int& a,const int& b){
	return a > b;  
}

bool dfs(int itr, int num, int nowLen) {
	if (num == 0)
		return true;

	int knowNum = -1;
	for (int i = itr; i < n; i++) {
		if (vis[i] || stick[i] == knowNum)
			continue;
		vis[i] = 1;
		if (nowLen + stick[i] < len) {
			if (dfs(itr + 1, num, nowLen + stick[i]))
				return true;
			knowNum = stick[i];
		}
		else if (nowLen + stick[i] == len) {
			if (dfs(0, num - 1, 0))
				return true;
			knowNum = stick[i];
		}
		vis[i] = 0;
		if (nowLen == 0)
			break;
	}

	return false;
}

int main() {
	while (scanf("%d", &n), n != 0) {
		sum = 0;
		for (int i = 0; i < n; i++) {
			scanf("%d", &stick[i]);
			sum += stick[i];
		}

		sort(stick, stick + n, cmp);

		for (int i = stick[0]; i <= sum; i++) {
			if (sum%i != 0) continue;
			ms(vis, 0);
			len = i;
			if (dfs(0, sum / i, 0)) {
				printf("%d\n", i);
				break;
			}
		}
	}

	return 0;
}