Submission #1165657

#	Time	Username	Problem	Language	Result	Execution time	Memory
1165657		SmuggingSpun	Swapping Cities (APIO20_swap)	C++20	100 / 100	411 ms	28776 KiB

swap

#include<bits/stdc++.h>
#include "swap.h"
using namespace std;
template<class T>void minimize(T& a, T b){
    if(a > b){
        a = b;
    }
}
template<class T>bool maximize(T& a, T b){
    if(a < b){
        a = b;
    }
}
const int lim = 1e5 + 5;
const int INF = 1e9;
bool is_sub1 = true, is_sub2;
int n, m, u[lim << 1], v[lim << 1], w[lim << 1];
vector<int>ei, g[lim];
namespace sub1{
    int max_w;
    void init(){
        if(m == n){
            max_w = *max_element(w, w + m);
        }
    }
}
namespace sub2{
    int third;
    void init(){
        if(n > 3){
            vector<int>p(n - 1);
            iota(p.begin(), p.end(), 1);
            sort(p.begin(), p.end(), [&] (int i, int j){
                return w[g[i][0]] < w[g[j][0]];
            });
            third = p[2];
        }
    }
}
struct PersistentDSU{
    vector<pair<int, int>>parent[lim], max_deg[lim];
    int cache_time = -1, size[lim], deg[lim], cycle_time[lim];
    void init(){
        for(int i = 0; i < n; i++){
            parent[i].emplace_back(-(size[i] = 1), i);
            max_deg[i].emplace_back(-1, deg[i] = 0);
            cycle_time[i] = INF;
        }
    }
    int find_set(int N, int time){
        while(true){
            int par_N = parent[N][upper_bound(parent[N].begin(), parent[N].end(), make_pair(time, INF)) - parent[N].begin() - 1].second;
            if(N == par_N){
                break;
            }
            N = par_N;
        }
        return N;
    }
    void merge(int u, int v){
        int U = u, V = v;
        if((u = find_set(u, ++cache_time)) != (v = find_set(v, cache_time))){
            if(size[u] < size[v]){
                swap(u, v);
            }
            parent[v].emplace_back(cache_time, u);
            size[u] += size[v];
        }
        else{
            minimize(cycle_time[u], cache_time);
        }
        int temp = max({max_deg[v].back().second, ++deg[U], ++deg[V]});
        if(temp > max_deg[u].back().second){
            max_deg[u].emplace_back(cache_time, temp);
        }
    }
    int get_max_deg(int N, int time){
        return max_deg[N][upper_bound(max_deg[N].begin(), max_deg[N].end(), make_pair(time, INF)) - max_deg[N].begin() - 1].second;
    }
    bool have_cycle(int N, int time){
        return cycle_time[N] <= time;
    }
};
PersistentDSU dsu;
void init(int N, int M, vector<int>U, vector<int>V, vector<int>W){
    n = N;
    m = M;
    for(int i = 0; i < m; i++){
        g[u[i] = U[i]].emplace_back(i);
        g[v[i] = V[i]].emplace_back(i);
        w[i] = W[i];
    }
    for(int i = 0; i < n; i++){
        if(g[i].size() > 2){
            is_sub1 = false;
            break;
        }
    }
    if(is_sub1){
        sub1::init();
        return;
    }
    if(is_sub2 = (*max_element(u, u + m) == 0 && m == n - 1)){
        sub2::init();
        return;
    }
    dsu.init();
    ei.resize(m);
    iota(ei.begin(), ei.end(), 0);
    sort(ei.begin(), ei.end(), [&] (int i, int j){
        return w[i] < w[j];
    });
    for(int& i : ei){
        dsu.merge(u[i], v[i]);
    }
}
int getMinimumFuelCapacity(int x, int y){
    if(is_sub1){
        return m == n - 1 ? -1 : sub1::max_w;
    }
    if(is_sub2){
        if(x == 0){
            return n < 4 ? -1 : max(w[g[y][0]], w[g[sub2::third][0]]);
        }
        return n < 4 ? -1 : max({w[g[x][0]], w[g[y][0]], w[g[sub2::third][0]]});
    }
    int low = 0, high = m - 1, ans = -1;
    while(low <= high){
        int mid = (low + high) >> 1, X = dsu.find_set(x, mid), Y = dsu.find_set(y, mid);
        if(X == Y && (dsu.have_cycle(X, mid) || dsu.get_max_deg(X, mid) > 2)){
            ans = w[ei[mid]];
            high = mid - 1;
        }
        else{
            low = mid + 1;
        }
    }
    return ans;
}

Compilation message (stderr)

swap.cpp: In function 'bool maximize(T&, T)':
swap.cpp:13:1: warning: no return statement in function returning non-void [-Wreturn-type]
   13 | }
      | ^

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