网络延迟时间

keep intensify2026-03-30 8:56

class Solution {

public:

int networkDelayTime(vector<vector<int>>& times, int n, int k) {

vector<vector<pair<int, int>>> graph(n);

for (auto& t : times) {

int u = t $0$ - 1, v = t $1$ - 1;

graph $u$ .emplace_back(v, t $2$ );

}

priority_queue<pair<int, int>, vector<pair<int, int>>,

greater<pair<int, int>>>

pq;

pq.push({0, k-1});

vector<int> dist(n, INT_MAX - 10000);

vector<bool> st(n, false);

dist $k-1$ =0;

while (pq.size()) {

auto e = pq.top();

pq.pop();

int w = e.first, u = e.second;

if (st $u$ )

continue;

st $u$ = true;

for (auto& o : graph $u$ ) {

int v = o.first, ww = o.second;

if (!st $v$ && dist $v$ > dist $u$ + ww) {

dist $v$ = dist $u$ + ww;

pq.push({dist $v$ , v});

}

int res = 0;

for (int i = 0; i < n; ++i) {

if (dist $i$ == INT_MAX - 10000)

return -1;

res = max(res, dist $i$ );

}

return res;

}

};