제출 #38884

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
38884		cheater2k	관광 (NOI14_sightseeing)	C++14	15 / 25	2699 ms	91456 KiB

sightseeing

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

const int N = 500005;

int n, m, q;
int dsu[N];
vector< pair<int, pair<int,int> > > edges;
vector< pair<int,int> > G[N];
int mn[N];

int anc(int p) { return p == dsu[p] ? p : dsu[p] = anc(dsu[p]); }
void join(int p, int q) { p = anc(p); q = anc(q); dsu[p] = q; }

int main() {
	scanf("%d %d %d", &n, &m, &q);
	for (int i = 0; i < m; ++i) {
		int u, v, w; scanf("%d %d %d", &u, &v, &w);
		edges.push_back(make_pair(w, make_pair(u, v))); // w <= 1e5
	}
	// build maximum spanning tree
	for (int i = 1; i <= n; ++i) dsu[i] = i;
	sort(edges.begin(), edges.end());
	for (int i = m - 1; i >= 0; --i) {
		int w = edges[i].first;
		int u = edges[i].second.first;
		int v = edges[i].second.second;
		if (anc(u) == anc(v)) continue;
		join(u, v);
		G[u].push_back(make_pair(w, v));
		G[v].push_back(make_pair(w, u));
	}

	for (int i = 1; i <= n; ++i) mn[i] = -1;
	mn[1] = 1e9;
	// bfs
	queue <int> qu; qu.push(1);
	while(!qu.empty()) {
		int u = qu.front(); qu.pop();
		for (int i = 0; i < G[u].size(); ++i) {
			int v = G[u][i].second, w = G[u][i].first;
			if (mn[v] == -1) {
				mn[v] = min(mn[u], w); qu.push(v);
			}
		}
	}
	
	// answer queries
	while(q-- > 0) {
		int u; scanf("%d", &u);
		printf("%d\n", mn[u]);
	}
}

컴파일 시 표준 에러 (stderr) 메시지

sightseeing.cpp: In function 'int main()':
sightseeing.cpp:40:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < G[u].size(); ++i) {
                     ^
sightseeing.cpp:16:31: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d %d", &n, &m, &q);
                               ^
sightseeing.cpp:18:45: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   int u, v, w; scanf("%d %d %d", &u, &v, &w);
                                             ^
sightseeing.cpp:50:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   int u; scanf("%d", &u);
                         ^

• Subtask 1: 4 / 4
• Subtask 2: 5 / 5
• Subtask 3: 6 / 6
• Subtask 4: 0 / 10