Submission #288420

#	Time	Username	Problem	Language	Result	Execution time	Memory
288420		Kastanda	Sorting (IOI15_sorting)	C++11	100 / 100	206 ms	17832 KiB

sorting

// M
#include<bits/stdc++.h>
#include "sorting.h"
using namespace std;
const int N = 200005 * 3;
int n, m, S[N], X[N], Y[N];
int A[N], M[N], Rev[N];
inline bool Solve(int md)
{
        for (int i = 0; i < n; i ++)
                A[i] = S[i], M[i] = 0;
        for (int i = 0; i < md; i ++)
                swap(A[X[i]], A[Y[i]]);

        int Cnt = 0;
        for (int i = 0; i < n; i ++)
                if (!M[i])
                {
                        int nw = i;
                        while (!M[nw])
                                M[nw] = 1, nw = A[nw];
                        Cnt ++;
                }
        Cnt = n - Cnt;
        return Cnt <= md;
}
int findSwapPairs(int _n, int _S[], int _m, int _X[], int _Y[], int P[], int Q[])
{
        n = _n; m = _m;
        for (int i = 0; i < n; i ++)
                S[i] = _S[i];
        for (int i = 0; i < m; i ++)
                X[i] = _X[i], Y[i] = _Y[i];

        {
                bool fail = 0;
                for (int i = 1; i < n; i ++)
                        if (S[i] < S[i - 1])
                                fail = 1;
                if (!fail)
                        return 0;
        }

        int le = 0, ri = m, md;
        while (ri - le > 1)
        {
                md = (le + ri) >> 1;
                if (Solve(md))
                        ri = md;
                else
                        le = md;
        }

        assert(Solve(ri));

        for (int i = 0; i < n; i ++)
                A[i] = S[i], M[i] = 0;
        for (int i = 0; i < ri; i ++)
                swap(A[X[i]], A[Y[i]]);

        vector < pair < int , int > > E;
        for (int i = 0; i < n; i ++)
                if (!M[i])
                {
                        int nw = i;
                        vector < int > vec;
                        while (!M[nw])
                        {
                                vec.push_back(nw);
                                M[nw] = 1;
                                nw = A[nw];
                        }
                        reverse(vec.begin(), vec.end());
                        for (int j = 1; j < (int)vec.size(); j ++)
                                E.push_back(make_pair(vec[j - 1], vec[j]));
                }
        assert(E.size() <= ri);
        for (int i = 0; i < n; i ++)
                A[i] = S[i];
        for (int i = 0; i < n; i ++)
                Rev[A[i]] = i;

        for (int i = 0; i < ri; i ++)
        {
                swap(A[X[i]], A[Y[i]]);
                swap(Rev[A[X[i]]], Rev[A[Y[i]]]);
                if (!E.size())
                {
                        P[i] = Q[i] = 0;
                        continue;
                }

                int a = E.back().first;
                int b = E.back().second;
                E.pop_back();

                int ra = Rev[a];
                int rb = Rev[b];

                P[i] = ra;
                Q[i] = rb;

                swap(A[ra], A[rb]);
                swap(Rev[A[ra]], Rev[A[rb]]);
        }
        return ri;


}

Compilation message (stderr)

In file included from /usr/include/c++/9/cassert:44,
                 from /usr/include/x86_64-linux-gnu/c++/9/bits/stdc++.h:33,
                 from sorting.cpp:2:
sorting.cpp: In function 'int findSwapPairs(int, int*, int, int*, int*, int*, int*)':
sorting.cpp:77:25: warning: comparison of integer expressions of different signedness: 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   77 |         assert(E.size() <= ri);
      |                ~~~~~~~~~^~~~~

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