Submission #594610

#	Time	Username	Problem	Language	Result	Execution time	Memory
594610		davi_bart	Sorting (IOI15_sorting)	C++14	100 / 100	181 ms	22576 KiB

sorting

#pragma GCC optimize("O3")
#include <bits/stdc++.h>

#include "sorting.h"
using namespace std;
#define ll long long
// #define int ll
#define fi first
#define se second
#define ld long double
#define pb push_back
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int N;
vector<int> v;
vector<int> ini;
vector<pair<int, int>> scambi;
vector<bool> vis(200010);
void dfs(int pos, int ini) {
    vis[pos] = 1;
    scambi.pb({pos, v[pos]});
    if (v[pos] == ini) return;
    dfs(v[pos], ini);
}
int findSwapPairs(int N, int S[], int M, int P[], int Q[], int X[], int Y[]) {
    ::N = N;
    for (int i = 0; i < N; i++) v.pb(S[i]);
    ini = v;
    int ans = 0;
    int l = 0, r = N + 2;
    while (l < r) {
        int m = (l + r) / 2;
        v = ini;
        fill(vis.begin(), vis.begin() + N + 10, 0);
        scambi.clear();
        for (int i = 0; i < m; i++) {
            swap(v[P[i]], v[Q[i]]);
        }
        for (int j = 0; j < N; j++) {
            if (vis[j] || v[j] == j) continue;
            dfs(v[j], j);
        }
        if (scambi.size() <= m)
            r = m;
        else
            l = m + 1;
    }
    ans = l;
    v = ini;
    fill(vis.begin(), vis.begin() + N + 10, 0);
    scambi.clear();
    for (int i = 0; i < l; i++) {
        swap(v[P[i]], v[Q[i]]);
    }

    for (int j = 0; j < N; j++) {
        if (vis[j] || v[j] == j) continue;
        dfs(v[j], j);
    }
    v = ini;
    vector<int> pos(N);

    for (int j = 0; j < N; j++) {
        pos[v[j]] = j;
    }
    for (int i = 0; i < ans; i++) {
        swap(v[P[i]], v[Q[i]]);
        swap(pos[v[P[i]]], pos[v[Q[i]]]);

        if (i >= scambi.size()) {
            X[i] = 0;
            Y[i] = 0;
            continue;
        }
        X[i] = pos[scambi[i].fi];
        Y[i] = pos[scambi[i].se];
        // int k = pos[v[X[i]]];
        swap(v[X[i]], v[Y[i]]);
        swap(pos[v[X[i]]], pos[v[Y[i]]]);
    }
    return ans;
}

Compilation message (stderr)

sorting.cpp: In function 'void dfs(int, int)':
sorting.cpp:18:23: warning: declaration of 'ini' shadows a global declaration [-Wshadow]
   18 | void dfs(int pos, int ini) {
      |                   ~~~~^~~
sorting.cpp:15:13: note: shadowed declaration is here
   15 | vector<int> ini;
      |             ^~~
sorting.cpp: In function 'int findSwapPairs(int, int*, int, int*, int*, int*, int*)':
sorting.cpp:24:23: warning: declaration of 'N' shadows a global declaration [-Wshadow]
   24 | int findSwapPairs(int N, int S[], int M, int P[], int Q[], int X[], int Y[]) {
      |                   ~~~~^
sorting.cpp:13:5: note: shadowed declaration is here
   13 | int N;
      |     ^
sorting.cpp:42:27: warning: comparison of integer expressions of different signedness: 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   42 |         if (scambi.size() <= m)
      |             ~~~~~~~~~~~~~~^~~~
sorting.cpp:69:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   69 |         if (i >= scambi.size()) {
      |             ~~^~~~~~~~~~~~~~~~
sorting.cpp:24:39: warning: unused parameter 'M' [-Wunused-parameter]
   24 | int findSwapPairs(int N, int S[], int M, int P[], int Q[], int X[], int Y[]) {
      |                                   ~~~~^

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