Submission #1655888


Source Code Expand

#include <bits/stdc++.h>
using namespace std;

typedef long long LL;
const int Maxn = 111111;
struct Edge {
	int v, id;
	Edge *nxt;
} pool[Maxn*2], *tree[Maxn], *tail = pool;
inline void addedge(const int &u, const int &v, const int &id) {
	tail->v = v, tail->id = id;
	tail->nxt = tree[u], tree[u] = tail++;
}

int n, a[Maxn], w[Maxn];
bool isleaf[Maxn];

void dfs(int u, int fa, int lastid) {
	w[lastid] = a[u];
	isleaf[u] = true;
	for (Edge *p = tree[u]; p; p = p->nxt) {
		if (p->v != fa) {
			isleaf[u] = false;
			dfs(p->v, u, p->id);
			w[lastid] -= w[p->id];
		}
	}
	if (!isleaf[u]) {
		w[lastid] += a[u];
	}
}
void solve() {
	if (n == 2) {
		if (a[1] == a[2]) {
			puts("YES");
		} else {
			puts("NO");
		}
		return;
	}
	for (int i = 1, cnum; i <= n; ++i) {
		cnum = 0;
		for (Edge *p = tree[i]; p; p = p->nxt) {
			++cnum;
		}
		if (cnum > 1) {
			dfs(i, 0, 0);
			break;
		}
	}
	if (w[0] != 0) {
		puts("NO");
		return;
	}
	for (int i = 1; i < n; ++i) {
		if (w[i] < 0) {
			puts("NO");
			return;
		}
	}
	for (int i = 1; i <= n; ++i) {
		if (!isleaf[i]) {
			LL tot = 0;
			for (Edge *p = tree[i]; p; p = p->nxt) {
				tot += w[p->id];
			}
			for (Edge *p = tree[i]; p; p = p->nxt) {
				if (w[p->id] > tot/2) {
					puts("NO");
					return;
				}
			}
		}
	}
	puts("YES");
}

int main() {
	scanf("%d", &n);
	for (int i = 1; i <= n; ++i){
		scanf("%d", &a[i]);
	}
	for (int i = 1, x, y; i < n; ++i) {
		scanf("%d%d", &x, &y);
		addedge(x, y, i), addedge(y, x, i);
	}
	solve();
	return 0;
}

Submission Info

Submission Time
Task C - Cleaning
User vjudge5
Language C++14 (GCC 5.4.1)
Score 700
Code Size 1503 Byte
Status AC
Exec Time 39 ms
Memory 9088 KB

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:79:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &n);
                 ^
./Main.cpp:81:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &a[i]);
                     ^
./Main.cpp:84:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &x, &y);
                        ^

Judge Result

Set Name Sample All
Score / Max Score 0 / 0 700 / 700
Status
AC × 3
AC × 51
Set Name Test Cases
Sample sample1.txt, sample2.txt, sample3.txt
All sample1.txt, sample2.txt, sample3.txt, in1.txt, in10.txt, in11.txt, in12.txt, in13.txt, in14.txt, in15.txt, in16.txt, in17.txt, in18.txt, in19.txt, in2.txt, in20.txt, in21.txt, in22.txt, in23.txt, in24.txt, in25.txt, in26.txt, in27.txt, in28.txt, in29.txt, in3.txt, in30.txt, in31.txt, in32.txt, in33.txt, in34.txt, in35.txt, in36.txt, in37.txt, in38.txt, in39.txt, in4.txt, in40.txt, in41.txt, in42.txt, in43.txt, in44.txt, in45.txt, in5.txt, in6.txt, in7.txt, in8.txt, in9.txt, sample1.txt, sample2.txt, sample3.txt
Case Name Status Exec Time Memory
in1.txt AC 39 ms 5628 KB
in10.txt AC 35 ms 4992 KB
in11.txt AC 37 ms 8320 KB
in12.txt AC 37 ms 8320 KB
in13.txt AC 33 ms 9088 KB
in14.txt AC 33 ms 8448 KB
in15.txt AC 1 ms 256 KB
in16.txt AC 1 ms 256 KB
in17.txt AC 1 ms 256 KB
in18.txt AC 1 ms 256 KB
in19.txt AC 36 ms 4992 KB
in2.txt AC 35 ms 4992 KB
in20.txt AC 33 ms 4992 KB
in21.txt AC 33 ms 4992 KB
in22.txt AC 34 ms 4992 KB
in23.txt AC 35 ms 4992 KB
in24.txt AC 33 ms 4992 KB
in25.txt AC 1 ms 256 KB
in26.txt AC 34 ms 4992 KB
in27.txt AC 36 ms 4992 KB
in28.txt AC 1 ms 256 KB
in29.txt AC 32 ms 4992 KB
in3.txt AC 35 ms 4992 KB
in30.txt AC 1 ms 256 KB
in31.txt AC 33 ms 4992 KB
in32.txt AC 33 ms 4992 KB
in33.txt AC 35 ms 4992 KB
in34.txt AC 35 ms 4992 KB
in35.txt AC 33 ms 4992 KB
in36.txt AC 33 ms 4992 KB
in37.txt AC 2 ms 256 KB
in38.txt AC 33 ms 4992 KB
in39.txt AC 33 ms 4992 KB
in4.txt AC 35 ms 4992 KB
in40.txt AC 33 ms 4992 KB
in41.txt AC 33 ms 4992 KB
in42.txt AC 32 ms 4992 KB
in43.txt AC 34 ms 4992 KB
in44.txt AC 34 ms 4992 KB
in45.txt AC 33 ms 4992 KB
in5.txt AC 35 ms 4992 KB
in6.txt AC 35 ms 4992 KB
in7.txt AC 31 ms 4480 KB
in8.txt AC 9 ms 2944 KB
in9.txt AC 35 ms 4992 KB
sample1.txt AC 1 ms 256 KB
sample2.txt AC 1 ms 256 KB
sample3.txt AC 1 ms 256 KB