poj 木棒

#include<iostream>#include<stdio.h>#include<string.h>#include<functional>#include<algorithm>#include<fstream>using namespace std;int total, mx,sum;int sticks[100];bool used[100];bool dfs(int tobuild, int localleft, int totalleft,int tr){//tobuild表示尝试当前长度仍需要组成的木棒//localleft表示组成这根木棒还需要的长度//totalleft表示木棒剩余的木棒总长if(localleft == 0){tobuild -=1;localleft = tr;}if(tobuild == 0)return true;if(totalleft < localleft)return false;  //剩余长度不够组成一个int temp = 100;for(int i = 1; i <= total; ++i){if(!used[i] && sticks[i] <= localleft && sticks[i] != temp){used[i] = true;temp = sticks[i];if(dfs(tobuild,localleft-sticks[i],totalleft-sticks[i],tr)){return true;}used[i] = false;if(localleft == tr){return false;}}}return false;}int main(){//freopen("1.txt","r",stdin);while(scanf("%d",&total)&&total){mx = 0;sum = 0;memset(sticks,0,sizeof(sticks));memset(used,0,sizeof(used));for(int i = 1; i <= total;++i){scanf("%d",&sticks[i]);if(mx < sticks[i]){mx = sticks[i];}sum += sticks[i];}sort(sticks+1,sticks+1+total,greater<int>());for(int t = mx; t <= sum; ++t){if(sum % t) continue;else if(dfs(sum/t,t,sum,t)){printf("%d\n",t);break;}}}return 0;}

基本思想是dfs，注意剪枝~否则会超时