Submission #295687

#	Time	Username	Problem	Language	Result	Execution time	Memory
295687		jhnah917	Swapping Cities (APIO20_swap)	C++14	13 / 100	481 ms	54496 KiB

swap

#include "swap.h"
#include <bits/stdc++.h>
#define x first
#define y second
#define all(v) v.begin(), v.end()
#define compress(v) sort(all(v)), v.erase(unique(all(v)), v.end())
using namespace std;

typedef long long ll;
typedef pair<ll, ll> p;

struct Edge{
    int s, e, x;
    bool operator < (const Edge &t) const {
        return tie(x, s, e) < tie(t.x, t.s, t.e);
    }
};

int par[101010];
int find(int v){ return v == par[v] ? v : par[v] = find(par[v]); }
int merge(int u, int v){
    u = find(u); v = find(v);
    if(u == v) return 0;
    par[u] = v; return 1;
}

const int sz = 1 << 17;
struct Seg{
    int tree[1 << 18];
    void update(int x, int v){
        x |= sz; tree[x] = v;
        while(x >>= 1) tree[x] = max(tree[x << 1], tree[x << 1 | 1]);
    }
    int query(int l, int r){
        l |= sz; r |= sz; int ret = 0;
        while(l <= r){
            if(l & 1) ret = max(ret, tree[l++]);
            if(~r & 1) ret = max(ret, tree[r--]);
            l >>= 1; r >>= 1;
        }
        return ret;
    }
};

struct HLD{
    vector<p> inp[101010];
    vector<int> g[101010];
    int w[101010], pv;
    int in[101010], top[101010], dep[101010], sz[101010], par[101010];
    Seg seg;
    void dfs(int v, int b){
        for(auto i : inp[v]) if(i.x != b) {
            g[v].push_back(i.x); w[i.x] = i.y;
            dep[i.x] = dep[v] + 1; par[i.x] = v;
            dfs(i.x, v);
        }
    }
    void dfs1(int v){
        sz[v] = 1;
        for(auto &i : g[v]){
            dfs1(i); sz[v] += sz[i];
            if(sz[i] > sz[g[v][0]]) swap(i, g[v][0]);
        }
    }
    void dfs2(int v){
        in[v] = ++pv;
        for(auto i : g[v]){
            top[i] = i == g[v][0] ? top[v] : i;
            dfs2(i);
        }
    }
    void init(int n){
        dfs(0, -1); dfs1(0); dfs2(0);
        for(int i=0; i<n; i++) seg.update(in[i], w[i]);
    }
    int query(int u, int v){
        int ret = 0;
        for(; top[u] != top[v]; u=par[top[u]]){
            if(dep[top[u]] < dep[top[v]]) swap(u, v);
            ret = max(ret, seg.query(in[top[u]], in[u]));
        }
        if(dep[u] > dep[v]) swap(u, v);
        ret = max(ret, seg.query(in[u]+1, in[v]));
        return ret;
    }
    void addEdge(int s, int e, int x){
        inp[s].emplace_back(e, x);
        inp[e].emplace_back(s, x);
    }
} t1, t2;

int n, m, deg[101010], flag;
vector<Edge> edge;
vector<int> g[101010];

void init(int N, int M, vector<int> U, vector<int> V, vector<int> W) {
    n = N; m = M; edge.resize(m);
    for(int i=0; i<m; i++){
        edge[i].s = U[i]; edge[i].e = V[i]; edge[i].x = W[i];
        g[edge[i].s].push_back(edge[i].e);
        g[edge[i].e].push_back(edge[i].s);
    }
    sort(all(edge)); iota(par, par+101010, 0);
    for(auto i : edge){
        if(merge(i.s, i.e)) t1.addEdge(i.s, i.e, i.x), t2.addEdge(i.s, i.e, i.x);
        else{
            if(merge(i.s, n)) t2.addEdge(i.s, n, i.x);
            if(merge(i.e, n)) t2.addEdge(i.e, n, i.x);
        }
        if(++deg[i.s] == 3 && merge(i.s, n)) t2.addEdge(i.s, n, i.x);
        if(++deg[i.e] == 3 && merge(i.e, n)) t2.addEdge(i.e, n, i.x);
    }
    for(int i=0; i<n; i++) if(deg[i] >= 3) flag = 1;
    if(n <= m) flag = 1;
    t1.init(n); t2.init(n+1);
}

int getMinimumFuelCapacity(int a, int b) {
    if(!flag) return -1;
    return max({t1.query(a, b), (t2.query(a, n), t2.query(b, n))});
}

• Subtask 1: 6 / 6
• Subtask 2: 7 / 7
• Subtask 3: 0 / 17
• Subtask 4: 0 / 20
• Subtask 5: 0 / 23
• Subtask 6: 0 / 27