Graph/Shortest_path/Floyd_warshall.h

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• Last update: 2025-06-11 15:37:14+07:00

Depends on

• template.h

Verified with

• Graph/test/aizu_grl_1_c_floyd_warshall.test.cpp

Code

#include "../../template.h"

void initTrace(int n, vector<vector<int>> &trace) {
    for (int u = 1; u <= n; ++u) {
        for (int v = 1; v <= n; ++v) {
            trace[u][v] = u;
        }
    }
}

void floyd_warshall(int n, vector<vector<ll>> &dist, vector<vector<int>> &trace) {
    initTrace(n, trace);
    for (int k = 1; k <= n; ++k) {
        for (int u = 1; u <= n; ++u) {
            for (int v = 1; v <= n; ++v) {
                if (dist[u][k] != 1e18 && dist[k][v] != 1e18 && dist[u][v] > dist[u][k] + dist[k][v]) {
                    dist[u][v] = dist[u][k] + dist[k][v];
                    trace[u][v] = trace[k][v];
                }
            }
        }
    }
}

#line 2 "template.h"

#include <bits/stdc++.h>
using namespace std;
 
#define ll long long
#define MOD (ll)(1e9+7)
#define all(x) (x).begin(),(x).end()
#define unique(x) x.erase(unique(all(x)), x.end())
#define INF32 ((1ull<<31)-1)
#define INF64 ((1ull<<63)-1)
#define inf (ll)1e18

#define vi vector<int>
#define pii pair<int, int>
#define pll pair<ll, ll>
#define fi first
#define se second

const int mod = 998244353;

void solve();

int main(){
    ios_base::sync_with_stdio(false);cin.tie(NULL);
    // cin.exceptions(cin.failbit);
    // int t; cin >> t;
    // while(t--)
        solve();
    cerr << "\nTime run: " << 1000 * clock() / CLOCKS_PER_SEC << "ms" << '\n';
    return 0;
}
#line 2 "Graph/Shortest_path/Floyd_warshall.h"

void initTrace(int n, vector<vector<int>> &trace) {
    for (int u = 1; u <= n; ++u) {
        for (int v = 1; v <= n; ++v) {
            trace[u][v] = u;
        }
    }
}

void floyd_warshall(int n, vector<vector<ll>> &dist, vector<vector<int>> &trace) {
    initTrace(n, trace);
    for (int k = 1; k <= n; ++k) {
        for (int u = 1; u <= n; ++u) {
            for (int v = 1; v <= n; ++v) {
                if (dist[u][k] != 1e18 && dist[k][v] != 1e18 && dist[u][v] > dist[u][k] + dist[k][v]) {
                    dist[u][v] = dist[u][k] + dist[k][v];
                    trace[u][v] = trace[k][v];
                }
            }
        }
    }
}

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