Submission #1218417

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Source Code Expand

import std.stdio, std.array, std.string, std.conv, std.algorithm;
import std.typecons, std.range, std.random, std.math, std.container;
import std.numeric, std.bigint, core.bitop;

immutable int MAX = 3010;
immutable long MOD = 10^^9+7;

void main() {
    immutable int MMAX = 2*10^^6+1;

    auto modinv = new long[](MMAX);
    modinv[0] = modinv[1] = 1;
    foreach(i; 2..MMAX) {
        modinv[i] = modinv[MOD % i] * (MOD - MOD / i) % MOD;
    }

    auto f_mod = new long[](MMAX);
    auto f_modinv = new long[](MMAX);
    f_mod[0] = f_mod[1] = 1;
    f_modinv[0] = f_modinv[1] = 1;

    foreach(i; 2..MMAX) {
        f_mod[i] = (i * f_mod[i-1]) % MOD;
        f_modinv[i] = (modinv[i] * f_modinv[i-1]) % MOD;
    }

    long combi(int n, int k) {
        return f_mod[n] * f_modinv[n-k] % MOD * f_modinv[k] % MOD;
    }
    

    
    auto s = readln.split.map!(to!int);
    auto N = s[0];
    auto K = s[1];
    auto X = new int[](N);
    auto Y = new int[](N);
    foreach (i; 0..N) {
        s = readln.split.map!(to!int);
        X[i] = s[0];
        Y[i] = s[1];
    }


    auto A = new int[][](MAX+1, MAX+1);
    foreach (i; 0..N) A[X[i]+1][Y[i]+1] += 1;
    foreach (i; 0..MAX+1)
        foreach (j; 0..MAX)
            A[i][j+1] += A[i][j];
    foreach (j; 0..MAX+1)
        foreach (i; 0..MAX)
            A[i+1][j] += A[i][j];

    int cumsum(int x1, int y1, int x2, int y2) {
        return A[x2+1][y2+1] - A[x2+1][y1] - A[x1][y2+1] + A[x1][y1];
    }

    bool count(int x) {
        foreach (i; 0..MAX-x)
            foreach (j; 0..MAX-x)
                if (cumsum(i, j, i+x, j+x) >= K)
                    return true;
        return false;
    }

    int hi = MAX;
    int lo = -1;
    while (hi - lo > 1) {
        int mid = (hi + lo) / 2;
        if (count(mid)) hi = mid;
        else lo = mid;
    }


    long ans = 0;
    int cs;
    foreach (i; 0..MAX-hi) 
        foreach (j; 0..MAX-hi)
            if ((cs = cumsum(i, j, i+hi, j+hi)) >= K)
                ans = (ans + combi(cs, K)) % MOD;

    hi.writeln;
    ans.writeln;
}

Submission Info

Judge Result