c++最短路

dijkstra:

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
int a[3010][3010], d[3010];
bool v[3010];
int n, m;

void dijkstra() {
   
	memset(d, 0x3f, sizeof(d)); // dist数组
	memset(v, 0, sizeof(v)); // 节点标记
	d[1] = 0;
	for (int i = 1; i < n; i++) {
    // 重复进行n-1次
		int x = 0;
		// 找到未标记节点中dist最小的
		for (int j = 1; j <= n; j++)
			if (!v[j] && (x == 0 || d[j] < d[x])) x = j;
		v[x] = 1;
		// 用全局最小值点x更新其它节点
		for (int y = 1; y <= n; y++)
			d[y] = min(d[y], d[x] + a[x][y]);
	}
}

int main() {
   
	cin >> n >> m;
	// 构建邻接矩阵
	memset(a, 0x3f, sizeof(a));
	for (int i = 1; i <= n; i++) a[i][i] = 0;
	for (int i = 1; i <= m; i++) {
   
		int x, y, z;
		scanf("%d%d%d", &x, &y, &z);
		a[x][y] = min(a[x]<
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