Submission #1090883

#	Time	Username	Problem	Language	Result	Execution time	Memory
1090883		yogesh_sane	Group Photo (JOI21_ho_t3)	C++17	44 / 100	5072 ms	2908 KiB

Main

#include <iostream>
#include <vector>
#include <algorithm>
#include <numeric>
#include <queue>
using namespace std;

int n;
vector<int>a, idx;
vector<int>p;
int const inf = 1e9;
vector<int>dp;
vector<vector<int>>dpcost;
int cost(int pos, int val){
    if(dpcost[pos][val] != -1)
        return dpcost[pos][val];
    //cout << "cost(" << pos << ',' << val << ")\n";
    iota(p.begin(), p.end(), 0);
    reverse(p.begin()+pos, p.begin()+val+1);
    int inv = 0;
    for(int i = pos; i <= val; i++){
        for(int j = i+1; j <= n; j++){
            if((p[i] < p[j] && idx[i] > idx[j]) ||
               (p[i] > p[j] && idx[i] < idx[j]))
               inv++;
        }
    }
    return dpcost[pos][val] = inv;
}

int solve(int k){
    if(k > n)
        return 0;
    if(dp[k] != -1)
        return dp[k];
    //cout << "solve(" << k <<")" << endl;
    if(k > n)
        return 0;
    int ans = inf;    
    for(int i = k; i <= n; i++){
        ans = min(ans, cost(k, i) + solve(i+1));
    }
    return dp[k] = ans;
}
int main(){
    cin >> n;
    a.resize(n+1);
    p.resize(n+1);
    idx.resize(n+1);
    dp.resize(n+1, -1);
    dpcost.resize(n+1, vector<int>(n+1, -1));
    for(int i = 1; i <= n; i++){
        cin >> a[i];
        idx[a[i]] = i;
    }
    cout << solve(1) << '\n';
    return 0;
}

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 32 / 32
• Subtask 4: 0 / 20
• Subtask 5: 0 / 36