UVA 839 Not so Mobile

题意：判断一棵树是否符合力矩相等。

分析：递归。注意引用传值的使用。

#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<cctype>
#include<cmath>
#include<iostream>
#include<sstream>
#include<iterator>
#include<algorithm>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<stack>
#include<deque>
#include<queue>
#include<list>
typedef long long ll;
typedef unsigned long long llu;
const int INT_INF = 0x3f3f3f3f;
const int INT_M_INF = 0x7f7f7f7f;
const ll LL_INF = 0x3f3f3f3f3f3f3f3f;
const ll LL_M_INF = 0x7f7f7f7f7f7f7f7f;
const int dr[] = {0, 0, -1, 1};
const int dc[] = {-1, 1, 0, 0};
const double pi = acos(-1.0);
const double eps = 1e-8;
const int MAXN = 10000 + 10;
const int MAXT = 1000000 + 10;
using namespace std;
bool dfs(int &w){
    int wl, dl, wr, dr;
    scanf("%d%d%d%d", &wl, &dl, &wr, &dr);
    bool flag1 = true;
    bool flag2 = true;
    if(!wl){
        flag1 = dfs(wl);
    }
    if(!wr){
        flag2 = dfs(wr);
    }
    w = wl + wr;//因为传参，所以此处计算了两者父结点的重量
    return flag1 && flag2 && (wl * dl == wr * dr);
}
int main(){
    int T;
    scanf("%d", &T);
    while(T--){
        int w = 0;
        if(dfs(w)) printf("YES\n");
        else printf("NO\n");
        if(T) printf("\n");
    }
    return 0;
}