Submission #612439

#	Time	Username	Problem	Language	Result	Execution time	Memory
612439		yuto1115	Sorting (IOI15_sorting)	C++17	100 / 100	452 ms	27820 KiB

sorting

#include "sorting.h"
#include <bits/stdc++.h>
#define rep(i, n) for(ll i = 0; i < ll(n); ++i)
#define rep2(i, s, n) for(ll i = ll(s); i < ll(n); ++i)
#define rrep(i, n) for(ll i = ll(n)-1; i >= 0; --i)
#define rrep2(i, n, t) for(ll i = ll(n)-1; i >= ll(t); --i)
#define pb push_back
#define eb emplace_back
#define all(a) a.begin(),a.end()
#define SZ(a) int(a.size())
using namespace std;
using ll = long long;
using P = pair<int, int>;
using vi = vector<int>;
using vvi = vector<vi>;
using vl = vector<ll>;
using vvl = vector<vl>;
using vp = vector<P>;
using vvp = vector<vp>;
using vb = vector<bool>;
using vvb = vector<vb>;
using vs = vector<string>;
const int inf = 1001001001;
const ll linf = 1001001001001001001;

template<class T>
bool chmin(T &a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}

template<class T>
bool chmax(T &a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

int findSwapPairs(int n, int s[], int m, int x[], int y[], int p[], int q[]) {
    int ok = n - 1, ng = -1;
    auto f = [&](int i) -> bool {
        vi to(n);
        iota(all(to), 0);
        vi rev(n);
        iota(all(rev), 0);
        rep(j, i) {
            swap(to[rev[x[j]]], to[rev[y[j]]]);
            swap(rev[x[j]], rev[y[j]]);
        }
        vvi ls;
        vb seen(n);
        rep(j, n) {
            if (seen[j]) continue;
            ls.pb({});
            int now = j;
            while (true) {
                seen[now] = true;
                ls.back().pb(now);
                int nx = s[rev[now]];
                if (seen[nx]) break;
                now = nx;
            }
        }
        return n - SZ(ls) <= i;
    };
    while (ok - ng > 1) {
        int mid = (ok + ng) / 2;
        if (f(mid)) ok = mid;
        else ng = mid;
    }
    int i = ok;
    vi to(n);
    iota(all(to), 0);
    vi rev(n);
    iota(all(rev), 0);
    rep(j, i) {
        swap(to[rev[x[j]]], to[rev[y[j]]]);
        swap(rev[x[j]], rev[y[j]]);
    }
    vvi ls;
    vb seen(n);
    rep(j, n) {
        if (seen[j]) continue;
        ls.pb({});
        int now = j;
        while (true) {
            seen[now] = true;
            ls.back().pb(now);
            int nx = s[rev[now]];
            if (seen[nx]) break;
            now = nx;
        }
    }
    vp ev;
    for (const vi &v: ls) {
        rep2(j, 1, SZ(v)) ev.eb(v[0], v[j]);
    }
    rep(j, i) {
        swap(rev[to[x[j]]], rev[to[y[j]]]);
        swap(to[x[j]], to[y[j]]);
        if (j < SZ(ev)) {
            p[j] = rev[ev[j].first];
            q[j] = rev[ev[j].second];
        } else {
            p[j] = q[j] = 0;
        }
    }
    return i;
}

Compilation message (stderr)

sorting.cpp: In lambda function:
sorting.cpp:60:23: warning: conversion from 'll' {aka 'long long int'} to 'int' may change value [-Wconversion]
   60 |             int now = j;
      |                       ^
sorting.cpp: In function 'int findSwapPairs(int, int*, int, int*, int*, int*, int*)':
sorting.cpp:90:19: warning: conversion from 'll' {aka 'long long int'} to 'int' may change value [-Wconversion]
   90 |         int now = j;
      |                   ^
sorting.cpp:44:39: warning: unused parameter 'm' [-Wunused-parameter]
   44 | int findSwapPairs(int n, int s[], int m, int x[], int y[], int p[], int q[]) {
      |                                   ~~~~^

• Subtask 1: 8 / 8
• Subtask 2: 12 / 12
• Subtask 3: 16 / 16
• Subtask 4: 18 / 18
• Subtask 5: 20 / 20
• Subtask 6: 26 / 26