Floyd : City of Blinding Lights
- Time : O(n^3 + q)
- Space : O(n^2)
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| #include <bits/stdc++.h>
#pragma optimization_level 3
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx")
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimization ("unroll-loops")
struct PairHash {inline std::size_t operator()(const std::pair<int,int> & v) const {return v.first*31+v.second;}};
#define MAX_N 404
#define INF 987654321
#define EPS 1e-9
#define ll long long
#define pll pair<ll, ll>
#define vpll vector<pll>
#define vall3 vector<array<ll,3>>
#define all3 array<ll,3>
#define all5 array<ll,5>
#define vall5 vector<all5>
#define vll vector<ll>
#define vs vector<string>
#define usll unordered_set<ll>
#define uspll unordered_set<pll, PairHash>
#define vvs vector<vs>
#define vvll vector<vll>
#define all(a) begin(a), end(a)
using namespace std;
ll adj[MAX_N][MAX_N];
void floyd(ll n) {
for(ll k = 1; k <= n; k++) {
for(ll i = 1; i <= n; i++) {
for(ll j = 1; j <= n; j++) {
adj[i][j] = min(adj[i][j], adj[i][k] + adj[k][j]);
}
}
}
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
ll tc = 1;
for(ll i = 1; i <= tc; i++) {
ll n, m, q;
cin>>n>>m;
for(ll j = 1; j <= n; j++) for(ll k = 1; k <= n; k++) adj[j][k] = INT_MAX;
for(ll j = 0; j < m; j++) {
ll u, v, c;
cin>>u>>v>>c;
adj[u][v] = c;
}
floyd(n);
cin>>q;
for(ll j = 0; j < q; j++) {
ll u, v;
cin>>u>>v;
if(u == v) cout<<"0"<<endl;
else if(adj[u][v] >= INT_MAX) cout<<"-1"<<endl;
else cout<<adj[u][v]<<endl;
}
}
return 0;
}
|
