Submission #1092457

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;
typedef long long lint;
typedef pair<int, int> pi;

lint n, a[100005], b[100005], sum;
vector<int> gph[100005];

lint dfs(int x, int p){
	lint sum = 0;
	for(auto &i : gph[x]){
		if(i != p) sum += dfs(i, x);
	}
	if(sum == 0) return a[x];
	lint death = sum - a[x];
	lint alive = a[x] - death;
	if(death < 0 || alive < 0){
		puts("NO");
		exit(0);
	}
	return alive;
}

int main(){
	scanf("%lld",&n);
	for(int i=1; i<=n; i++){
		scanf("%lld",&a[i]);
	}
	for(int i=0; i<n-1; i++){
		int s, e;
		scanf("%d %d",&s,&e);
		gph[s].push_back(e);
		gph[e].push_back(s);
	}
	if(n == 2){
		puts(a[1] == a[2] ? "YES" : "NO");
		return 0;
	}
	for(int i=1; i<=n; i++){
		if(gph[i].size() > 1){
			if(dfs(i, -1) != 0){
				puts("NO");
				return 0;
			}
			puts("YES");
			return 0;
		}
	}
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:25:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%lld",&n);
                  ^
./Main.cpp:27:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%lld",&a[i]);
                      ^
./Main.cpp:31:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d",&s,&e);
                       ^

Judge Result