Submission #967595

#	Time	Username	Problem	Language	Result	Execution time	Memory
967595		GrindMachine	Sorting (IOI15_sorting)	C++17	100 / 100	260 ms	23660 KiB

sorting

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
 
using namespace std;
using namespace __gnu_pbds;
 
template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
 
#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) (int)a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x,y) ((x+y-1)/(y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl
 
#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)
 
template<typename T>
void amin(T &a, T b) {
    a = min(a,b);
}
 
template<typename T>
void amax(T &a, T b) {
    a = max(a,b);
}
 
#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif
 
/*
 
refs:
edi
 
*/
 
const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;
 
#include "sorting.h"
 
int findSwapPairs(int n, int a[], int m, int X[], int Y[], int P[], int Q[]) {
    if(is_sorted(a,a+n)) return 0;

    auto ok = [&](int mid, int t){
        vector<int> plates(n), plate_pos(n);
        iota(all(plates),0), iota(all(plate_pos),0);
        rep(i,mid){
            // swap plates x and y
            int x = X[i], y = Y[i];
            int &p = plate_pos[x], &q = plate_pos[y];
            swap(plates[p],plates[q]);
            swap(p,q);
        }
     
        vector<bool> vis(n);
        vector<pii> to_swap; // pairs of apples that need to be swapped
     
        rep(i,n){
            if(vis[i]) conts;
            int j = i;
            vector<int> apples;
     
            while(!vis[j]){
                vis[j] = 1;
                apples.pb(a[j]);
                j = plate_pos[a[j]];
            }
     
            rep(k,sz(apples)-1){
                to_swap.pb({apples[k],apples.back()});
            }
        }
        
        if(!t){
            return sz(to_swap) <= mid;
        }

        iota(all(plates),0), iota(all(plate_pos),0);
        vector<int> apples(n), apple_pos(n);
        rep(i,n) apples[i] = a[i], apple_pos[a[i]] = i;
        
        rep(i,mid){
            {
                int x = X[i], y = Y[i];
                int &p = plate_pos[x], &q = plate_pos[y];
                swap(plates[p],plates[q]);
                swap(p,q);
            }
     
            if(!to_swap.empty()){
                auto [x,y] = to_swap.back();
                to_swap.pop_back();
                int &p = apple_pos[x], &q = apple_pos[y];
                P[i] = plates[p], Q[i] = plates[q];
                swap(apples[p],apples[q]);
                swap(p,q);
            }
        }
        
        // rep(i,n) assert(plates[i] == apples[i]);
        return true;
    };

    int l = 1, r = m;
    int ans = -1;

    while(l <= r){
        int mid = (l+r) >> 1;
        if(ok(mid,0)){
            ans = mid;
            r = mid-1;
        }
        else{
            l = mid+1;
        }
    }

    ok(ans,1);
    return ans;
}

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