[알고리즘] 백준 5792번: 택배 배송 (C++)

https://www.acmicpc.net/problem/5972

5972번: 택배 배송

문제를 읽고, 그래프가 양방향 그래프인 것을 알고 다익스트라를 돌리면 된다.

#include <iostream>
#include <queue>
#include <utility>
#include <vector>
#define MAX 50000 + 1
#define INF 987654321
#define pii pair<int, int>
using namespace std;

int n, m;
vector<pii> graph[MAX];
int dist[MAX];

struct cmp {
	bool operator()(pii& a, pii& b) {
		return a.second > b.second;
	}
};

void dijkstra(int node) {
	dist[node] = 0;
	priority_queue<pii, vector<pii>, cmp> pq;
	pq.push({ node, 0 });

	while (!pq.empty()) {
		int now = pq.top().first;
		int cost = pq.top().second;

		pq.pop();
		if(dist[now] < cost){
			continue;
		}

		for (int i = 0; i < graph[now].size(); i++) {
			int next = graph[now][i].first;
			int nextCost = graph[now][i].second;

			if (cost + nextCost < dist[next]) {
				dist[next] = cost + nextCost;
				pq.push({ next, dist[next] });
			}
		}
	}
}

int main() {
	cin >> n >> m;
	for (int i = 0; i < m; i++) {
		int a, b, c;
		cin >> a >> b >> c;
		graph[a].push_back({ b, c });
		graph[b].push_back({ a, c });
	}

	for (int i = 1; i <= n; i++) {
		dist[i] = INF;
	}

	dijkstra(1);
	cout << dist[n];
	return 0;
}