最短路 HDU - 2544 (dijkstra算法或Floyd算法)

Dijkstra解法：

#include <stdio.h>
#include <iostream>
#include <cstring>
#include <vector>
#include <algorithm>
#include <sstream>

#define INF 1000000000

using namespace std;
int N, M;
int dist[101],g[101][101];
int vis[101];


void dijkstra(int start)
{
    for(int i = 1; i <= N; ++i)
    {
        dist[i] = g[start][i];
        vis[i] = 0;
    }
    vis[start] = 1; 
    
    while(1)
    {
        int mark = -1, minDist = INF;
        for(int i = 1; i <= N; ++i)
        {
            if(!vis[i] && dist[i] < minDist)
            {
                minDist = dist[i];
                mark = i;
            }
        }
        
        if(mark == -1)        // 找不到未收录的节点，则说明算法结束，退出 
            break;
            
        vis[mark] = 1;
        
        for(int i = 1; i <= N; ++i)
        {
            if(!vis[i])
                dist[i] = min(dist[i], dist[mark] + g[mark][i]);
        }
    }
}

int main()
{
    while(cin >> N >> M)
    {
        if(N == 0 && M == 0)
            break;

        for(int i = 1; i <= N; ++i)
            for(int j = 1; j <= N; ++j)
            {
                if(i == j)
                    g[i][j] = 0;
                else
                    g[i][j] = INF;
            }

        for(int i = 1; i <= M; ++i)
        {
            int a,b,c;
            cin >> a >> b >> c;
            g[a][b] = g[b][a] = c;
        }

        dijkstra(1);
        cout << dist[N] << endl;

    }

    return 0;
}

 

Floyd解法:

#include <stdio.h>
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <sstream>

using namespace std;

int dis[101][101];

int main()
{
       int N, M;
    while(cin >> N >> M)
    {
        if(N == 0 && M == 0)
            break;
        
        for(int i = 1; i <= N; ++i)
        {
            for(int j = 1; j <= N; ++j)
            {
                if(i == j)
                    dis[i][j] = 0;
                else
                    dis[i][j] = 1100000; 
            }
        }
        
        int a, b, c;
        for(int i = 1; i <= M; ++i)
        {
            cin >> a >> b >> c;
            if(dis[a][b] > c)
                dis[a][b] = dis[b][a] = c;
            
        }
        
        for(int k = 1; k <= N; ++k)
            for(int i = 1; i <= N; ++i)
                for(int j = 1; j <= N; ++j)
                {
                    if(dis[i][j] > dis[i][k] + dis[k][j])
                        dis[i][j] = dis[i][k] + dis[k][j];
                }
                
        cout << dis[1][N] << endl;
    } 
       
       
       
       
    return 0;
}