[算法] poj 2387 单源最短路 Dijkstra

单源最短路

#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <algorithm>
using namespace std;
const int N = 1005;
#define INF 0x7fffffff

int data[N][N];
int lowc[N];
bool vis[N];
int n, m;
void djst(int p) {
	for(int i = 1; i <= n; i++) {
		lowc[i] = data[p][i];
		vis[i] = false;
	}
	vis[p] = true;
	int i, j;
	for(i = 1; i <= n-1; i++) {
		int minv = INF, c = 0;
		for(j = 1; j <= n; j++) {
			if(!vis[j] && lowc[j] < minv) {
				minv = lowc[j];
				c = j;
			}
		}
		if(c == 1) {
			printf("%d\n", minv); 
			return;
		}
		vis[c] = true;
		for(j = 1; j <= n; j++) {
			if(!vis[j] && data[c][j] != INF && minv + data[c][j] < lowc[j]) {
				lowc[j] = minv + data[c][j];
			}
		}
	}
}
int main() {
	cin >> m >> n;
	for(int i = 1; i <= n; i++) {
		for(int j = 1; j <= n; j++) {
			data[i][j] = INF;
		}
	}
	int u, v, w;
	for(int i = 0; i < m; i++) {
		cin >> u >> v >>  w;
		if(w < data[u][v]) {
			data[u][v] = w;
			data[v][u] = w;
		}
	}
	djst(n);
	return 0;
}