ZOJ（1711）Sum It Up （DFS+剪枝+去重复）

#include <iostream>
#include <stdio.h>
#include <string>
#include <string.h>
#include <algorithm>
#include <math.h>
#include <fstream>
#include <vector>
#include <map>
#include <queue>
#include <stack>
#include <math.h>
#include <stdlib.h>
using namespace std ;
const int maxn = 15;
int x[maxn];
int t,n,sum,remain;
int vis[maxn];
int f_flag;
void dfs(int id){
    if(id==n||sum >= t){
        if(sum == t){
            f_flag = 0;
            int flag = 0;
            for(int i = 0;i < n;i++){
                if(vis[i]){
                    if(flag)
                        printf("+%d",x[i]);
                    else{
                        printf("%d",x[i]);
                        flag = 1;
                    }
                }
            }
            printf("\n");
        }
        return;
    }
    if(sum+x[id] <= t && x[id] != remain){
        sum += x[id];
        vis[id] = 1;
        dfs(id+1);
        sum -= x[id];
        vis[id] = 0;
    }
    remain = x[id];//记录上一个
    dfs(id+1);
}
int main(){
    while(scanf("%d%d",&t,&n)&&(t+n)){
        for(int i = 0;i < n;i++)
            scanf("%d",x+i);
        memset(vis,0,sizeof(vis));
        sum = 0;remain = 0;
        f_flag = 1;
        printf("Sums of %d:\n",t);
        dfs(0);
        if(f_flag)
            printf("NONE\n");
    }
    return 0 ;
}