1 #define INF 0x3f3f3f3f
2 const int maxn = 503;
3 #define _for(i,a,b) for(int i = (a);i < (b);i ++)
4 struct edge
5 {
6 int to;
7 int cost;
8 };
9
10 //G[s].push_back(t);from s to t,directed
11
12 class Solution
13 {
14 public:
15 int d[maxn];
16 int V,E;
17 vector<edge> G[maxn];
18 //from s to other V
19 void shortest_path(int s)
20 {
21 _for(i,0,V)
22 d[i] = INF;
23
24 d[s] = 0;
25 while(1)
26 {
27 bool update = false;
28 _for(i,0,V)
29 {
30 _for(j,0,G[i].size())
31 {
32 edge e = G[i][j];
33 if(d[i] != INF && d[e.to] > d[i] + e.cost)
34 {
35 d[e.to] = d[i] + e.cost;
36 update = true;
37 }
38 }
39 }
40 if(!update) break;
41 }
42 }
43 int networkDelayTime(vector<vector<int>>& times, int N, int K)
44 {
45 V = N;
46 _for(i,0,times.size())
47 {
48 G[times[i][0]-1].push_back(edge{times[i][1]-1,times[i][2]});
49 E ++;
50 }
51
52 shortest_path(K-1);
53 // cout << d[1] << endl;
54 int cnt = 0;
55 _for(i,0,V)
56 {
57 if(d[i]==INF) return -1;
58 cnt = max(cnt,d[i]);
59 }
60 return cnt;
61 }
62 };
