题解 | #最长全1串#

import java.util.Scanner;

public class Main {
    private static int n;
    private static int k;
    private static int[] nums;
    private static int[] sum;

    public static void main(String[] args){
        Scanner in = new Scanner(System.in);

        while(in.hasNext()){
            solution1(in);
            // solution2(in);
            // solution3(in);
        }
    }

    /**
     * 滑动窗口 + 双指针
     * @param in
     */
    private static void solution1(Scanner in){
        n = in.nextInt();
        k = in.nextInt();

        nums = new int[n];

        int i, j, zeros=0;
        for(i=0,j=0; j<n; j++){
            nums[j] = in.nextInt();
            if(nums[j] == 0){
                zeros++;
            }
            if(zeros>k && nums[i++]==0){
                zeros--;
            }
        }

        System.out.println(j-i);
    }

    /**
     * 动态规划
     * f[x] = i
     * f[x]表示第x个0在字符串中的位置为i
     * @param in
     */
    private static void solution2(Scanner in){
        n = in.nextInt();
        k = in.nextInt();

        int num, zeros=0, result=0;
        int[] f = new int[n+1];
        for(int i=0; i<n; i++){
            num = in.nextInt();
            if(num == 0){
                f[++zeros] = i;
            }
            if(zeros <= k){
                result = Math.max(result, i+1);
            }else{
                result = Math.max(result, i-f[zeros-k]);
            }
        }

        System.out.println(result);
    }

    /**
     * 二分法 + 数组
     * @param in
     */
    private static void solution3(Scanner in){
        n = in.nextInt();
        k = in.nextInt();

        nums = new int[n+1];
        sum = new int[n+1];

        for(int i=1; i<=n; i++){
            nums[i] = in.nextInt();
            sum[i] = sum[i-1]+nums[i];
        }

        int l = 0;
        int r = n;
        while(l <= r){
            int mid = (l+r)>>1;
            if(!isOk(mid)) {
                r = mid-1;
            }else{
                l = mid+1;
            }
        }

        System.out.println(r);
    }

    /**
     * 当前区间可否全为1
     * @param gap
     * @return
     */
    private static boolean isOk(int gap){
        int zeros;
        for(int j=0; j+gap<=n; j++){
            zeros = gap-(sum[j+gap]-sum[j]);
            if(k >= zeros){
                return true;
            }
        }

        return false;
    }
}