Submission #3767806

---

Source Code Expand

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

#define MAX_N 10000

long long par[MAX_N]; // 親
long long rankuf[MAX_N]; // 木の深さ
// n要素で初期化
void init(long long n) {
	for (long long i = 0; i < n; i++) {
		par[i] = i;
    rankuf[i] = 0;
	}
}
// 木の根を求める
long long find(long long x) {
	if (par[x] == x) {
		return x;
	} else {
		return par[x] = find(par[x]);
	}
}
// xとyの属する集合を併合
void unite(long long x, long long y) {
	x = find(x);
	y = find(y);
	if (x == y) return;
	if (rankuf[x] < rankuf[y]) {
		par[x] = y;
	} else {
		par[y] = x;
		if (rankuf[x] == rankuf[y]) rankuf[x]++;
	}
}
// xとyが同じ集合に属するか否か
bool same(long long x, long long y) {
	return find(x) == find(y);
}

void solve(long long N, long long M, long long u[], long long v[]){
	init(N);

	for (int i = 0 ; i <= M-1 ; i++) {
		unite(u[i], v[i]);
	}

	long long vcount[N-1+1];
	long long ecount[N-1+1];
	long long check[N-1+1];
	memset(vcount, 0, sizeof(vcount));
	memset(ecount, 0, sizeof(ecount));
  memset(check, 0, sizeof(check));

	for (int i = 0 ; i <= M-1 ; i++) {
		if (check[u[i]] == 0) {
			check[u[i]] = 1;
			vcount[find(u[i])]++;
		}
		if (check[v[i]] == 0) {
			check[v[i]] = 1;
			vcount[find(v[i])]++;
		}
		ecount[find(u[i])]++;
	}

	long long res = 0;
	for (int i = 0 ; i <= N-1 ; i++) {
		if (ecount[i] + 1 == vcount[i]) res++;
		if (vcount[i] == 0 && ecount[i] == 0 && find(i) == i) res++;
	}
	printf("%lld\n", res);
}

int main(){
	long long M;
	long long N;
	scanf("%lld",&N);
	scanf("%lld",&M);
	long long u[M-1+1];
	long long v[M-1+1];
	for(int i = 0 ; i <= M-1 ; i++){
		scanf("%lld",&u[i]);
		scanf("%lld",&v[i]);
		u[i]--;
		v[i]--;
	}
	solve(N, M, u, v);
	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:77:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%lld",&N);
                  ^
./Main.cpp:78:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%lld",&M);
                  ^
./Main.cpp:82:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%lld",&u[i]);
                      ^
./Main.cpp:83:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%lld",&v[i]);
                      ^

Judge Result