47 lines
1.9 KiB
C++
47 lines
1.9 KiB
C++
class Graph {
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public:
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vector<vector<int>> dist;
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int num;
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Graph(int n, vector<vector<int>>& edges) {
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num=n;
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dist=vector<vector<int>>(n,vector<int>(n,INT_MAX));//所有端点之间距离初始化为无穷大
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for (int i=0;i<n;i++) dist[i][i]=0;//自己到自己的距离为0
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int m=edges.size();
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for (int i=0;i<m;i++){
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dist[edges[i][0]][edges[i][1]]=edges[i][2]; //添加一条边，左端点到右端点的距离为cost
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}
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for (int k=0;k<n;k++){ //对于每一个端点，看它是否可以作为中间点连接另外两个端点a和b，如果比直接连接ab更近，则更新ab之间的最短距离
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for (int i=0;i<n;i++){
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for (int j=0;j<n;j++){
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if (dist[i][k] != INT_MAX && dist[k][j] != INT_MAX){
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dist[i][j] = min (dist[i][j], dist[i][k]+dist[k][j]);
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}
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}
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}
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}
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}
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void addEdge(vector<int> edge) {
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if (edge[2]>dist[edge[0]][edge[1]]) //如果添加的边的权值大于已有最短路径权值，不需要更新dist[][]，直接返回
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return;
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for (int i=0;i<num;i++){ //对于每一对端点ij，看是否可以通过edge作为中间边连接，比直接连接ij更近，则更新ij之间的最短距离
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for (int j=0;j<num;j++){
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if (dist[i][edge[0]] != INT_MAX && dist[edge[1]][j] != INT_MAX){
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dist[i][j] = min (dist[i][j], dist[i][edge[0]]+dist[edge[1]][j]+edge[2]);
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}
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}
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}
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}
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int shortestPath(int node1, int node2) {
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return dist[node1][node2]==INT_MAX?-1:dist[node1][node2];
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}
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};
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/**
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* Your Graph object will be instantiated and called as such:
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* Graph* obj = new Graph(n, edges);
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* obj->addEdge(edge);
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* int param_2 = obj->shortestPath(node1,node2);
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*/
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