Submission #923933

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Source Code Expand

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Scanner;
import java.util.function.BiFunction;

public class Main {
  Scanner sc = new Scanner(System.in);

  public static void main(String[] args) {
    new Main().run();
  }

  void run() {
    int n = ni();
    int k = ni();
    long[] a = new long[n];
    for (int i = 0; i < n; ++i) {
      a[i] = ni();
    }
    int l = 0;
    int r = k;
    long sum = 0;
    long sub = 0;
    for (int j = l; j < r; ++j) {
      sub += a[j];
    }
    sum += sub;
    for (int i = 0; r < n; ++i) {
      sub -= a[l++];
      sub += a[r++];
      sum += sub;
    }
    System.out.println(sum);
  }

  int ni() {
    return Integer.parseInt(sc.next());
  }

  void debug(Object... os) {
    System.err.println(Arrays.deepToString(os));
  }

  class BIT<T> {
    int n;
    ArrayList<T> bit;
    BiFunction<T, T, T> bif;

    BIT(int n, BiFunction<T, T, T> bif, T defaultValue) {
      this.n = n;
      bit = new ArrayList<>(n + 1);
      for (int i = 0; i < n + 1; ++i) {
        bit.add(defaultValue);
      }
      this.bif = bif;
    }

    void update(int i, T v) {
      for (int x = i; x <= n; x += x & -x) {
        bit.set(x, bif.apply(bit.get(x), v));
      }
    }

    T reduce(int i, T defaultValue) {
      T ret = defaultValue;
      for (int x = i; x > 0; x -= x & -x) {
        ret = bif.apply(ret, bit.get(x));
      }
      return ret;
    }
  }
}

Submission Info

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