Submission #922122

#TimeUsernameProblemLanguageResultExecution timeMemory
922122406Swapping Cities (APIO20_swap)C++17
100 / 100
428 ms57204 KiB
    //happier ending for folks like us? 
    //yani in AC nashe, yak yak kesaii ke in APIO dadan dast ma
    //PAIN
    #include "swap.h"
    #include <bits/stdc++.h>
    using namespace std;
    const int N = 4e5 + 15, M = 2e5 + 5, L = 21, INF = 0x3f3f3f3f;
    int p[N], dpr[N], pr[N][L], ext[N], P[N], h[N], rt, D[N], deg[N];
    vector<int> adj[N], Wtmp;
    inline void smin(int &a, int b) {a = min(a, b);}
    void dfs(int v) {
    	for (int i = 1; i < L; i++) pr[v][i] = pr[pr[v][i - 1]][i - 1];
    	for (auto u: adj[v]) {
    		pr[u][0] = v;
    		h[u] = h[v] + 1;
    		dfs(u);
    		smin(ext[v], ext[u]);
    	}
    }
    int gpr(int u) {return dpr[u] == u ? u : dpr[u] = gpr(dpr[u]);}
    bool merge(int u, int v, int id) {
    	int tu = u, tv = v;
    	deg[tu]++, deg[tv]++;
    	u = gpr(u), v = gpr(v);
    	if (u == v) return false;
    	dpr[u] = dpr[v] = id + M;
    	D[id + M] = max({D[u], D[v], deg[tu], deg[tv]});
    	adj[id + M].push_back(u);
    	adj[id + M].push_back(v);
    	return true;
    }
    void init(int n, int m, std::vector<int> U, std::vector<int> V, std::vector<int> W) {
    	iota(p, p + m, 0);
    	sort(p, p + m, [&](const int x, const int y) {return W[x] < W[y];});
    	iota(dpr, dpr + N, 0);
    	memset(ext, 0x3f, sizeof ext);
    	Wtmp = W;
    	for (int i = 0; i < m; i++) {
    		const int id = p[i];
    		if (!merge(U[id], V[id], id)) {
    			smin(ext[U[id]], W[id]);
    			smin(ext[V[id]], W[id]);
    		}
    	}
    	rt = gpr(0), pr[rt][0] = rt, dfs(rt);
    }
    int LCA(int X, int Y) {
    	for (int i = L - 1; i >= 0; i--) if (pr[Y][i] != pr[X][i]) Y = pr[Y][i], X = pr[X][i];
    	return pr[X][0];
    }
    int getMinimumFuelCapacity(int X, int Y) {
    	if (h[X] < h[Y]) swap(X, Y);
    	while (h[Y] < h[X]) X = pr[X][__lg(h[X] - h[Y])];
    	int w = INF, lca = LCA(X, Y);
    	for (int i = L - 1; i >= 0; i--) if (pr[Y][i] != pr[X][i] || D[pr[X][i]] <= 2) Y = pr[Y][i], X = pr[X][i];
    	smin(w, (D[pr[X][0]] > 2 ? Wtmp[pr[X][0] - M] : INF));
    	if (h[X] <= h[lca]) smin(w, max(Wtmp[X - M], ext[X]));
    	return w >= INF ? -1 : w;
    }
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