网易严选建有N个自营仓分布在全国各地，标记为仓库1到N。 给定一个配货时间组（v,u,w)，v为出发仓库，u为目标仓库，w为从出发仓库到目标仓库的耗时时间。可能存在仓库间过远，无法支持调拨转货。 指定一个出发仓库K，我们需要将供应商发送到K仓库的货配送到各个仓库。问配送到所有可到达仓库所要最短时间？如果无法全部调拨到，则返回-1.-笔试面试资料

懒得写dijskra了。。就Floyd应付一下

int dijskra(vector<vector<int>>& graph, int N, int source) {     for (int k = 1; k <= N; ++k) {         for (int i = 1; i <= N; ++i) {             for (int j = 1; j <= N; ++j) {                 if (graph[i][k] != INT_MAX && graph[k][j] != INT_MAX)                     graph[i][j] = min(graph[i][j], graph[i][k] + graph[k][j]);             }         }     }     int ans = INT_MIN;     for (int i = 1; i <= N; ++i) {         ans = max(ans, graph[source][i]);     }     if (ans == INT_MAX)return -1;     return ans; } int main() {     int N, K, M, v, u, w;     cin >> N >> K >> M;     vector<vector<int>> graph(N + 1, vector<int>(N + 1, INT_MAX));     for (int i = 0; i < M; ++i) {         cin >> v >> u >> w;         graph[v][u] = w;     }     for (int i = 0; i < N; ++i) {         graph[i][i] = 0;     }     cout << dijskra(graph, N, K);     return 0; }