Dijkstra算法实现-优快云博客

本文链接：https://blog.youkuaiyun.com/qqchenjunwei/article/details/14492415

本文介绍了一个使用Dijkstra算法解决带权图中单源最短路径问题的C++实现。通过初始化距离矩阵并采用贪心策略逐步更新顶点的距离与经过边的权重，找到从起点到所有其他顶点的最短路径及最小代价。

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#include <iostream>
#include <cstdio>
#include <cstring>

using namespace std;
const int M = 1005;
const int MAX = 0x7fffffff;
int dp[M][M];
int cont[M][M];
int vist[M];
int dir[M];
int value[M];
int n, m;

void init() {


    for(int i = 1; i <= n; i++) {

        for(int j = 1; j <= n; j++) {

            dp[i][j] = MAX;
            cont[i][j] = MAX;
        }
    }
}

void  dijkstra(int u) {

    int index;

  for(int i = 1; i <= n; i++) {

    dir[i] = dp[u][i];
    value[i] = cont[u][i];
    vist[i] = 0;
  }


  vist[u] = 1;
  dir[u] = 0;
  value [u] = 0;
  for(int i = 1; i <= n; i++) {

    int minn = MAX;
    for(int j = 1; j <= n; j++) {

        if(!vist[j] && dir[j] < minn)
        {
            minn = dir[j];
            index = j;
        }
    }
        if(minn == MAX)
            break;
        vist[index] = 1;
        for(int k = 1; k <= n; k++) {
           if(!vist[k] &&dp[index][k] < MAX ) {

            if(dir[k] > dir[index] + dp[index][k])
            {
                dir[k] = dir[index] + dp[index][k];
                    value[k] = value[index] + cont[index][k];
            }
            else if(dir[k] == dir[index] + dp[index][k])
            {
                 if(value[k] > value[index] + cont[index][k])
                {
                    value[k] = value[index] + cont[index][k];
                }
            }
           }
        }
  }

}
int main()
{
    int a, b, c, d;
    int s, e;
    while(scanf("%d%d", &n, &m) != EOF) {
          if(n == 0 && m == 0)
            break;
        init();

        for(int i = 1; i <= m; i++) {

            scanf("%d%d%d%d", &a, &b, &c, &d);
            if(dp[a][b] > c) {

                dp[a][b] = dp[b][a] = c;
                cont[a][b] = cont[b][a] = d;
            }
            else if(dp[a][b] == c) {

                if(cont[a][b] > d) {
                   cont[a][b] = cont[b][a] = d;
                }
            }

        }
        scanf("%d%d", &s, &e);

        dijkstra(s);
        printf("%d %d\n", dir[e], value[e]);
    }
    return 0;
}