hdu4277USACO ORZ dfs暴力枚举+map

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//给N个 问rails用着N个rails能构成几个不同的三角形//dfs暴力枚举+（map）#include<cstdio>#include<cstring>#include<map>#include<iostream>using namespace std ;int ans ;int a[20] ;int n ;int sum  =  0 ;struct node{    int a , b , c ;    bool operator == (const node d)const    {return (d.a==a&&d.b==b&&d.c==c);}};bool operator < (const node d , const node e){    if(d.a == e.a)    {        if(d.b == e.b)        return d.c < e.c ;        return d.b < e.b ;    }    return d.a < e.a;}bool operator == (const node d , const node e){return (d.a==e.a&&d.b==e.b&&d.c==e.c);}map<node , int> ma ;void dfs(int sum_1 , int sum_2 , int sum_3 ,int pos){    if(sum_1 > sum/2 || sum_2 > sum/2 || sum_3 > sum/2)    return ;    if(pos == n + 1)    {        if(sum_1 <= sum_2 && sum_2 <= sum_3)        if(sum_2 + sum_3 > sum_1 && sum_3)        {            struct node  a = {sum_1 , sum_2 , sum_3} ;            if(ma[a] == 0)            {                ans++ ;                ma[a] = 1;            }        }        return ;    }    dfs(sum_1+a[pos] , sum_2 , sum_3 , pos+1) ;    dfs(sum_1 , sum_2 + a[pos] , sum_3 , pos+ 1) ;    dfs(sum_1 , sum_2 , sum_3+ a[pos] , pos+1) ;}int main(){   //freopen("in.txt" ,"r" , stdin) ;    int T ;    scanf("%d" ,&T) ;    while(T--)    {        sum =  0 ;        scanf("%d" ,&n) ;        for(int i = 1;i <= n;i++)        scanf("%d" ,&a[i]) ,sum += a[i] ;        ans = 0 ;ma.clear() ;        dfs(0 , 0 , 0 ,1) ;        printf("%d\n" ,ans) ;    }}
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