Submission #1146655

#	Time	Username	Problem	Language	Result	Execution time	Memory
1146655		guagua0407	Sorting (IOI15_sorting)	C++17	100 / 100	104 ms	22388 KiB

sorting

#include "sorting.h"
//#include "grader.cpp"
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int,int>
#define f first
#define s second
#define all(x) x.begin(),x.end()
#define _ ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

int n,m;
vector<int> p;
vector<int> x,y;
vector<pair<int,int>> vec;

bool check(int mid){
    vector<int> pp=p;
    for(int i=0;i<mid;i++){
        swap(pp[x[i]],pp[y[i]]);
    }
    vector<bool> vis(n);
    vec.clear();
    for(int i=0;i<n;i++){
        if(vis[i]) continue;
        int cur=i;
        while(!vis[cur]){
            vis[cur]=true;
            if(pp[cur]!=i){
                vec.push_back({cur,pp[cur]});
            }
            cur=pp[cur];
        }
    }
    while((int)vec.size()<mid){
        vec.push_back({0,0});
    }
    if((int)vec.size()<=mid) return true;
    else return false;
}

int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {
    n=N;
    m=M;
    p.resize(n);
    x.resize(m);
    y.resize(m);
    for(int i=0;i<n;i++){
        p[i]=S[i];
    }
    for(int i=0;i<m;i++){
        x[i]=X[i];
        y[i]=Y[i];
        P[i]=0;
        Q[i]=0;
    }
    int l=0,r=m;
    while(l<r){
        int mid=(l+r)/2;
        if(check(mid)){
            r=mid;
        }
        else{
            l=mid+1;
        }
    }
    check(l);
    reverse(all(vec));
    vector<int> val(n);
    vector<int> rev(n);
    for(int i=0;i<n;i++){
        val[i]=rev[i]=i;
    }
    for(int i=l-1;i>=0;i--){
        P[i]=rev[vec[i].f];
        Q[i]=rev[vec[i].s];
        swap(val[x[i]],val[y[i]]);
        swap(rev[val[x[i]]],rev[val[y[i]]]);
    }
    return l;
}

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