Submission #1047426

#	Time	Username	Problem	Language	Result	Execution time	Memory
1047426		NotLinux	Arranging Shoes (IOI19_shoes)	C++17	50 / 100	42 ms	13148 KiB

shoes

#include <bits/stdc++.h>
#include "shoes.h"
using namespace std;
#define sz(x) (int)x.size()
#define all(x) x.begin(),x.end()
const long long inf = 1e18 + 7;
struct SEGT{
    vector < int > t;
    int tree_size;
    const int identity_element = 0;
    int merge(int x , int y){ 
        return x + y;
    }
    void init(int x){
        tree_size = x+3;
        t.assign(2*tree_size , identity_element);
    }
    void modify(int p, int value) {  // set value at position p
        for (t[p += tree_size] = value; p > 1; p >>= 1){
            t[p>>1] = merge(t[p] , t[p^1]); 
        }
    }
    int query(int l, int r) {  // sum on interval [l, r]
        int res = identity_element;
        for (r+=1 , l += tree_size, r += tree_size; l < r; l >>= 1, r >>= 1) {
            if (l&1) res = merge(res , t[l++]); 
            if (r&1) res = merge(res , t[--r]); 
        }
        return res;
    }
};
long long count_swaps(vector<int> s) {
	int n = sz(s) / 2;
	long long ans = inf;
	// cout << "n : " << n << endl;
	// for(auto itr : s)cout << itr << " ";cout << endl;
	if(n == 1){// 10 pts - n = 1
		ans = 0;
		if(s[0] > 0)ans++;
		return ans;
	}
	if(n <= 8){// 20 pts - n <= 8
		vector < int > shoes;
		for(auto itr : s)if(itr > 0)shoes.push_back(itr);
		vector < int > perm(n);
		iota(all(perm) , 0);
		do{	
			vector < int > tmp = s;
			long long locans = 0;
			vector < int > news;
			for(auto itr : perm){
				news.push_back(-shoes[itr]);
				news.push_back(shoes[itr]);
			}
			for(int i = 0;i<2*n;i++){
				int cur = i;
				while(tmp[cur] != news[i] and cur < (2 * n))cur++;
				assert(cur != (2*n));
				locans += cur - i;
				int tmp_val = tmp[cur];
				for(int j = cur;j>i;j--){
					tmp[j] = tmp[j-1];
				}	
				tmp[i] = tmp_val;
			}
			ans = min(ans , locans);
		} while(next_permutation(all(perm)));
		return ans;
	}
	set < int > ste;
	for(auto itr : s){
		ste.insert(abs(itr));
	}
	if(sz(ste) == 1){// 20 pts - all shoe sizes are same
		ans = 0;
		SEGT segt;
		segt.init(2 * n + 5);
		int sayac0 = 1 , sayac1 = 2;
		for(int i = 0;i<2*n;i++){
			if(s[i] < 0){
				ans += segt.query(sayac0 , 2*n);
				segt.modify(sayac0 , 1);
				sayac0+=2;				
			}
			else{
				ans += segt.query(sayac1 , 2*n);
				segt.modify(sayac1 , 1);
				sayac1+=2;
			}
		}
		return ans;
	}
	// else{// 15 pts - first n are left , rest are right and i = i+n

	// }
}

Compilation message (stderr)

shoes.cpp: In function 'long long int count_swaps(std::vector<int>)':
shoes.cpp:70:14: warning: control reaches end of non-void function [-Wreturn-type]
   70 |  set < int > ste;
      |              ^~~

• Subtask 1: 10 / 10
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 0 / 15
• Subtask 5: 0 / 20
• Subtask 6: 0 / 15