Submission #1112613

#	Time	Username	Problem	Language	Result	Execution time	Memory
1112613		vjudge1	Chessboard (IZhO18_chessboard)	C++17	47 / 100	2067 ms	9700 KiB

chessboard

//Dost SEFEROĞLU
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2")
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pii pair<int,int>
#define ff first
#define ss second
#define sp << " " << 
#define vi vector<int>
#define all(xx) xx.begin(),xx.end()
#define ps(xxx) cout << (xxx) << endl;
const int N = 5e2+1,inf = 1e16,MOD = 1e9+7; 
 

int32_t t[400001],lazy[400001];
inline void push(const int& node,const int& l,const int& r) {
    if (!lazy[node]) return;
    t[node] = (r-l+1)-t[node];
    if (l != r) {
        lazy[2*node]^=1;
        lazy[2*node+1]^=1;
    }
    lazy[node] = 0;
}
void update(int node,int l,int r,int L,int R) {
    push(node,l,r);
    if (l > R || r < L) return;
    if (l >= L && r <= R) {
        lazy[node]^=1;
        push(node,l,r);
        return;
    }
    int m = (l+r) >> 1;
    update(2*node,l,m,L,R),update(2*node+1,m+1,r,L,R);
    t[node] = t[2*node]+t[2*node+1];
}
void solve() { 
    int n,k;
    cin >> n >> k;
    vector<pii> upds[n+2];
    for (int i=1;i<=k;i++) {
        int x1,y1,x2,y2;
        cin >> x1 >> y1 >> x2 >> y2;
        upds[x1].push_back({y1,y2});
        upds[x2+1].push_back({y1,y2});
    }
    vi divs;
    for (int i=1;i<n;i++) if (n%i == 0) divs.push_back(i);
    int ans = inf;
    for (int d : divs) {
        int cur = 1;
        int fl = 0;
        while (cur <= n) {
            if (!fl) update(1,1,n,cur,cur+d-1);
            cur+=d;
            fl^=1;
        }
        int need = 0;
        for (int j = 1;j<=n+1;j++) {
            for (auto it : upds[j]) update(1,1,n,it.ff,it.ss);
            if (j > n) break;
            push(1,1,n);
            int q = t[1];
            if (((j-1)/d)%2 == 0) need+=q;
            else need+=n-q;
        }
        ans = min(ans,need);
        ans = min(ans,n*n-need);
        cur = 1;
        fl = 0;
        while (cur <= n) {
            if (!fl) update(1,1,n,cur,cur+d-1);
            cur+=d;
            fl^=1;
        }
    }
    cout << ans << endl;
}  
 
                
                            
signed main() { 
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    #ifdef Dodi
        freopen("in.txt","r",stdin);
        freopen("out.txt","w",stdout);
    #endif
    int t = 1;
    //cin >> t; 
    while (t --> 0) solve();
}

• Subtask 1: 8 / 8
• Subtask 2: 8 / 8
• Subtask 3: 15 / 15
• Subtask 4: 16 / 16
• Subtask 5: 0 / 23
• Subtask 6: 0 / 30