graph/spfa.hpp

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Last update: 2021-09-12 23:20:08-04:00
Include: #include "graph/spfa.hpp"

Depends on

template.hpp

Verified with

tests/graph/spfa.test.cpp

Code

#pragma once
#include "../template.hpp"

template <typename GraphType, typename EdgeType> vector<typename EdgeType::WeightType> spfa(int N, GraphType &g, initializer_list<int> start, typename EdgeType::WeightType initDis) {
    static EdgeType E;
    using w_t = typename EdgeType::WeightType;
    vector<w_t> dis(N+1, initDis);
    vector<int> inq(N+1, false);
    queue<int> q;
    for (auto s : start) {
        q.push(s);
        dis[s] = 0;
        inq[s] = false;
    }
    while (!q.empty()) {
        int c = q.front(); q.pop();
        inq[c] = false;
        for (auto _to : g[c]) {
            int to = E.v(_to); w_t alt = dis[c] + E.w(_to);
            if (alt < dis[to]) {
                dis[to] = alt;
                if (!inq[to]) {
                    inq[to] = true;
                    q.push(to);
                }
            }
        }
    }
    return dis;
}

#line 2 "template.hpp"
#include <bits/stdc++.h>
#define DEBUG 1
using namespace std;

// Defines
#define fs first
#define sn second
#define pb push_back
#define eb emplace_back
#define mpr make_pair
#define mtp make_tuple
#define all(x) (x).begin(), (x).end()
// Basic type definitions
#if __cplusplus == 201703L // CPP17 only things
template <typename T> using opt_ref = optional<reference_wrapper<T>>; // for some templates
#endif
using ll = long long; using ull = unsigned long long; using ld = long double;
using pii = pair<int, int>; using pll = pair<long long, long long>;
#ifdef __GNUG__
// PBDS order statistic tree
#include <ext/pb_ds/assoc_container.hpp> // Common file
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
template <typename T, class comp = less<T>> using os_tree = tree<T, null_type, comp, rb_tree_tag, tree_order_statistics_node_update>;
template <typename K, typename V, class comp = less<K>> using treemap = tree<K, V, comp, rb_tree_tag, tree_order_statistics_node_update>;
// HashSet
#include <ext/pb_ds/assoc_container.hpp>
template <typename T, class Hash> using hashset = gp_hash_table<T, null_type, Hash>;
template <typename K, typename V, class Hash> using hashmap = gp_hash_table<K, V, Hash>;
const ll RANDOM = chrono::high_resolution_clock::now().time_since_epoch().count();
struct chash { ll operator()(ll x) const { return x ^ RANDOM; } };
#endif
// More utilities
int SZ(string &v) { return v.length(); }
template <typename C> int SZ(C &v) { return v.size(); }
template <typename C> void UNIQUE(vector<C> &v) { sort(v.begin(), v.end()); v.resize(unique(v.begin(), v.end()) - v.begin()); }
template <typename T, typename U> void maxa(T &a, U b) { a = max(a, b); }
template <typename T, typename U> void mina(T &a, U b) { a = min(a, b); }
const ll INF = 0x3f3f3f3f, LLINF = 0x3f3f3f3f3f3f3f3f;
#line 3 "graph/spfa.hpp"

template <typename GraphType, typename EdgeType> vector<typename EdgeType::WeightType> spfa(int N, GraphType &g, initializer_list<int> start, typename EdgeType::WeightType initDis) {
    static EdgeType E;
    using w_t = typename EdgeType::WeightType;
    vector<w_t> dis(N+1, initDis);
    vector<int> inq(N+1, false);
    queue<int> q;
    for (auto s : start) {
        q.push(s);
        dis[s] = 0;
        inq[s] = false;
    }
    while (!q.empty()) {
        int c = q.front(); q.pop();
        inq[c] = false;
        for (auto _to : g[c]) {
            int to = E.v(_to); w_t alt = dis[c] + E.w(_to);
            if (alt < dis[to]) {
                dis[to] = alt;
                if (!inq[to]) {
                    inq[to] = true;
                    q.push(to);
                }
            }
        }
    }
    return dis;
}