Handstand

题目描述

$N$ people are arranged in a row from left to right. You are given a string $S$ of length $N$ consisting of $0$ and $1$, and a positive integer $K$. The $i$-th person from the left is standing on feet if the $i$-th character of $S$ is $0$, and standing on hands if that character is $1$. You will give the following direction at most $K$ times (possibly zero): Direction: Choose integers $l$ and $r$ satisfying $1 \leq l \leq r \leq N$, and flip the $l$-th, $(l+1)$-th, $...$, and $r$-th persons. That is, for each $i = l, l+1, ..., r$, the $i$-th person from the left now stands on hands if he/she was standing on feet, and stands on feet if he/she was standing on hands. Find the maximum possible number of consecutive people standing on hands after at most $K$ directions.

输入格式

Input is given from Standard Input in the following format: $N$ $K$ $S$

输出格式

Print the maximum possible number of consecutive people standing on hands after at most $K$ directions.

5 1
00010

4

14 2
11101010110011

8

1 1
1

1

提示

$N$ is an integer satisfying $1 \leq N \leq 10^5$. $K$ is an integer satisfying $1 \leq K \leq 10^5$. The length of the string $S$ is $N$. Each character of the string $S$ is $0$ or $1$.We can have four consecutive people standing on hands, which is the maximum result, by giving the following direction:

Give the direction with $l = 1, r = 3$, which flips the first, second and third persons from the left.
No directions are necessary.

标签: AtCoder|abc124D

来源

AtCoder|abc124D