Submission #958615

#	Time	Username	Problem	Language	Result	Execution time	Memory
958615		12345678	Sorting (IOI15_sorting)	C++17	36 / 100	2 ms	2600 KiB

sorting

#include "sorting.h"
#include <bits/stdc++.h>
 
using namespace std;
 
const int nx=2e5+5;

int s[nx], rs[nx], loc[nx], idx[nx], ridx[nx], n;

int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {
    n=N;
    int l=0, r=N-1;
    while (l<=r)
    {
        int md=(l+r)/2, cnt=0, cur=0;
        for (int i=0; i<N; i++) idx[i]=i, ridx[i]=i, s[i]=S[i], rs[s[i]]=i;
        for (int i=md-1; i>=0; i--) swap(idx[X[i]], idx[Y[i]]), swap(ridx[idx[X[i]]], ridx[idx[Y[i]]]);
        //cout<<"debug "<<l<<' '<<r<<' '<<md<<'\n';
        for (int i=0; i<md; i++)
        {
            swap(ridx[idx[X[i]]], ridx[idx[Y[i]]]);
            swap(idx[X[i]], idx[Y[i]]);
            swap(s[X[i]], s[Y[i]]);
            swap(rs[s[X[i]]], rs[s[Y[i]]]);
            /*
            cout<<"idx "<<md<<':';
            for (int j=0; j<N; j++) cout<<idx[j]<<' ';
            cout<<'\n';
            cout<<"ridx "<<md<<':';
            for (int j=0; j<N; j++) cout<<ridx[j]<<' ';
            cout<<'\n';
            cout<<"s "<<md<<':';
            for (int j=0; j<N; j++) cout<<s[j]<<' ';
            cout<<'\n';
            cout<<"rs "<<md<<':';
            for (int j=0; j<N; j++) cout<<rs[j]<<' ';
            cout<<'\n';
            */
            while (cur<N&&ridx[cur]==rs[cur]) cur++;
            if (cur<N) P[cnt]=ridx[cur], Q[cnt]=rs[cur], swap(s[P[cnt]], s[Q[cnt]]), swap(rs[s[P[cnt]]], rs[s[Q[cnt]]]), cur++, cnt++;
            while (cur<N&&ridx[cur]==rs[cur]) cur++;
        }
        //cout<<"debug "<<l<<' '<<r<<' '<<cur<<' '<<md<<'\n';
        if (l==r) return l;
        if (cur<N) l=md+1;
        else r=md;

    }
}

Compilation message (stderr)

sorting.cpp: In function 'int findSwapPairs(int, int*, int, int*, int*, int*, int*)':
sorting.cpp:10:39: warning: unused parameter 'M' [-Wunused-parameter]
   10 | int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {
      |                                   ~~~~^
sorting.cpp:49:1: warning: control reaches end of non-void function [-Wreturn-type]
   49 | }
      | ^

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