123 lines
2.9 KiB
C++
123 lines
2.9 KiB
C++
#include <bits/stdc++.h>
|
||
|
||
using namespace std;
|
||
|
||
|
||
#pragma region Dijkstra算法模板
|
||
//正无穷
|
||
const int INF = 0x3f3f3f3f;
|
||
//声明数据的最大维度
|
||
const int N = 100;
|
||
|
||
int n, m;
|
||
|
||
//初始数据
|
||
int mapp[N][N];
|
||
|
||
bool visited[N];
|
||
//距离,就是从1号顶点到其余各个顶点的初始路程
|
||
int dist[N];
|
||
|
||
//与求最短路相比，增加一个path数组，来记录最短路的路径,先将path[i]=-1，之后每次找出最短路的点p后将path[j]=p,用path[j]=i表示从i到j最短路的路径
|
||
int path[N];
|
||
|
||
|
||
/**
|
||
* 功能：迪杰斯特拉算法
|
||
* 试题板子
|
||
* @param v 计算哪个节点做为起始点到各节点的距离
|
||
*/
|
||
void Dijkstra(int v) {
|
||
//初始化
|
||
for (int i = 1; i <= n; i++) {
|
||
dist[i] = mapp[v][i];
|
||
visited[i] = 0;
|
||
path[i] = -1;
|
||
}
|
||
visited[v] = 1;
|
||
for (int i = 1; i <= n; i++) {
|
||
int p, minn = INF;
|
||
for (int j = 1; j <= n; j++) {
|
||
if (!visited[j] && dist[j] < minn) {
|
||
p = j;
|
||
minn = dist[j];
|
||
}
|
||
}
|
||
visited[p] = 1;
|
||
for (int j = 1; j <= n; j++) {
|
||
if (!visited[j] && dist[p] + mapp[p][j] < dist[j]) {
|
||
dist[j] = dist[p] + mapp[p][j];
|
||
path[j] = p;
|
||
}
|
||
}
|
||
}
|
||
return;
|
||
}
|
||
|
||
/**
|
||
* 功能：输出路径
|
||
* @param s 起点
|
||
* @param n 节点数量
|
||
*/
|
||
void print(int s, int n) {
|
||
stack<int> q;
|
||
for (int i = 2; i <= n; i++) {
|
||
int p = i;
|
||
while (path[p] != -1) {
|
||
q.push(p);
|
||
p = path[p];
|
||
}
|
||
q.push(p);
|
||
cout << s << "-->" << i << " ";
|
||
cout << "dis" << ":" << dist[i] << " ";
|
||
cout << s;
|
||
while (!q.empty()) {
|
||
cout << "-->" << q.top();
|
||
q.pop();
|
||
}
|
||
cout << endl;
|
||
}
|
||
}
|
||
|
||
#pragma endregion Dijkstra算法模板
|
||
|
||
int main() {
|
||
//输入+输出重定向
|
||
freopen("../1410.txt", "r", stdin);
|
||
|
||
//n:哨所数
|
||
//m:通信线路数
|
||
cin >> n >> m;
|
||
|
||
//1、初始化二维数组，全部为一个非常大的数据
|
||
for (int i = 0; i <= n; i++) {
|
||
for (int j = 0; j <= n; j++) {
|
||
mapp[i][j] = INF;
|
||
}
|
||
}
|
||
|
||
//2、s表示路径的起点，t表示路径的终点，edge表示该路径的长度。
|
||
int i, j, k;
|
||
//录入路径
|
||
while (m--) {
|
||
cin >> i >> j >> k;
|
||
//将权写入
|
||
mapp[i][j] = k;
|
||
mapp[j][i] = k; //反向写入，无向图
|
||
}
|
||
|
||
//3、调用核心算法: 源点（统一规定为v1）到所有其他各定点的最短路径长度。
|
||
Dijkstra(1);
|
||
|
||
//输出结果
|
||
int maxTime = 0;
|
||
for (int i = 2; i <= n; i++) {
|
||
if (dist[i] > maxTime) maxTime = dist[i];
|
||
}
|
||
if (maxTime == INF) cout << "-1" << endl;
|
||
else cout << maxTime << endl;
|
||
//关闭文件
|
||
fclose(stdin);
|
||
return 0;
|
||
}
|