Submission #496701

#	Time	Username	Problem	Language	Result	Execution time	Memory
496701		kevin	Sorting (IOI15_sorting)	C++17	0 / 100	1 ms	588 KiB

sorting

#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define vi vector<int>
#define all(x) x.begin(), x.end()
#define ca(v) for(auto i:v) cout<<i<<" ";
#define nl cout<<"\n"

const int MAXN = 5e5 + 5;

int findSwapPairs(int N, int* s, int M, int* X, int* Y, int* P, int* Q){
    int l = 0;
    int r = M-1;
    int ans = M;
    vi S;
    for(int i=0; i<N; i++) S.push_back(s[i]);
    while(l <= r){
        int m = (l+r)/2;
        vi ar = S;
        for(int i=0; i<=m; i++){
            swap(ar[X[i]], ar[Y[i]]);
        }
        int cnt = 0;
        vi vis(N, 0);
        for(int i=0; i<N; i++) {
            if(vis[i]) continue;
            cnt++;
            int q = i;
            while(1){
                vis[q] = 1;
                if(vis[ar[q]]) break;
                q = ar[q];
            }
        }
        cnt = N - cnt;
        if(cnt-1 <= m){
            ans = m;
            r = m-1;
        }
        else l = m+1;
    }
    vi vis(N, 0);
    vi ar = S;
    for(int i=0; i<=ans; i++) swap(ar[X[i]], ar[Y[i]]);
    vi xm, ym;
    int cnt = 0;
    for(int i=0; i<N; i++) {
        if(vis[i]) continue;
        cnt++;
        int q = i;
        while(1){
            vis[q] = 1;
            if(vis[ar[q]]) break;
            xm.push_back(q);
            ym.push_back(ar[q]);
            q = ar[q];
        }
    }
    vector<int> pos(N);
    for(int i=0; i<N; i++) pos[S[i]] = i;
    for(int i=0; i<xm.size(); i++){
        swap(pos[S[X[i]]], pos[S[Y[i]]]);
        swap(S[X[i]], S[Y[i]]);
        P[i] = pos[S[xm[i]]];
        Q[i] = pos[S[ym[i]]];
    }
    for(int i=0; i<N - cnt; i++){
        P[i+xm.size()] = 0;
        S[i+xm.size()] = 0;
    }
    return ans+1;
}

// int main()
// {
//     // ios_base::sync_with_stdio(0); cin.tie(0);
//     if (fopen("input.in", "r")) freopen("input.in", "r", stdin);
//     int N, M; cin>>N>>M;
//     int S[N], X[M], Y[M], P[M], Q[M];
//     for(int i=0; i<M; i++) P[i] = Q[i] = 0;
//     for(int i=0; i<N; i++) cin>>S[i];
//     for(int i=0; i<M; i++) cin>>X[i]>>Y[i];
//     cout<<findSwapPairs(N, S, M, X, Y, P, Q);
//     nl;
//     ca(P); nl;
//     ca(Q); nl;
// }

Compilation message (stderr)

sorting.cpp: In function 'int findSwapPairs(int, int*, int, int*, int*, int*, int*)':
sorting.cpp:62:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   62 |     for(int i=0; i<xm.size(); i++){
      |                  ~^~~~~~~~~~

• Subtask 1: 0 / 8
• Subtask 2: 0 / 12
• Subtask 3: 0 / 16
• Subtask 4: 0 / 18
• Subtask 5: 0 / 20
• Subtask 6: 0 / 26