Submission #679055

#	Time	Username	Problem	Language	Result	Execution time	Memory
679055		kusssso	Arranging Shoes (IOI19_shoes)	C++17	100 / 100	82 ms	57140 KiB

shoes

#include<bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 1e6 + 5;

int n;
int bit[N];
ll ans;
vector<int> pos[N][2];

void Update (int p, int v) {
    for (int i = p; i < N; i += i & -i) bit[i] += v;
}

int Get (int p) {
    int ret = 0;
    for (int i = p; i >= 1; i -= i & -i) ret += bit[i];
    return ret;
}

int Get (int l, int r) {
    return Get(r) - Get(l - 1);
}

ll count_swaps (vector<int> S) {
    n = S.size();
    for (int i = 1; i <= n; i++) {
        Update(i, 1);
        pos[abs(S[i - 1])][S[i - 1] < 0].push_back(i);
    }
    for (int i = 1; i <= n; i++) {
        for (int j = 0; j < 2; j++) {
            reverse(pos[i][j].begin(), pos[i][j].end());
        }
    }
    for (int i = 1; i <= n; i++) {
        if (!S[i - 1]) 
            continue;
            
        int &x = S[i - 1]; 
        // cerr << x << '\n';  
        int t = (x < 0);
        int j = pos[abs(x)][t ^ 1].back();
        pos[abs(x)][t ^ 1].pop_back();
        pos[abs(x)][t].pop_back();
        x = 0;
        S[j - 1] = 0;
        
        Update(j, -1);
        ans += (t ? Get(i + 1, j) : Get(i, j));
    }   
    return ans;
}

// signed main() {
    // ios_base::sync_with_stdio(0);
    // cin.tie(0);
//     
    // vector<int> S = {2, 1, -1, -2};
    // cout << count_swaps(S);
//     
    // return 0;
// }

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