校招真题练习012 最长全1串(美团)

最长全1串

题目描述
给你一个01字符串，定义答案=该串中最长的连续1的长度，现在你有至多K次机会，每次机会可以将串中的某个0改成1，现在问最大的可能答案

输入描述:
输入第一行两个整数N,K，表示字符串长度和机会次数
第二行输入N个整数，表示该字符串的元素
( 1 <= N <= 300000
, 0 <= K <= N )

输出描述:
输出一行表示答案

def getMax(B:'List[int]'):
    n = len(B)
    maxlen = 0
    curlen = 0
    for i in range (n):
        if B[i] == 1:
            curlen += 1
        else:
            maxlen = max(maxlen,curlen)
            curlen = 0
    return max(maxlen,curlen)

def longestOnes(A: 'List[int]', K: int) -> int:
    if K == 0:
        return getMax(A)
    n = len(A)
    zlist = list()
    for i in range(n):
        if A[i] == 0:
            zlist.append(i)
    if len(zlist)<=K:
        return n
    maxlen = 0
    for zi in range(len(zlist)-K+1):        
        ti = zi+K            
        left = 0
        right = len(A)-1
        if zi==0:
            left = zlist[zi]
        else:
            left = zlist[zi-1]+1
        if zi == len(zlist)-K:
            right = len(A) - 1
        else:
            right = zlist[ti] - 1
        maxlen = max(maxlen, right - left +1)    
    return maxlen

if __name__ == '__main__':
    line0 = list(map(int,input().strip().split()))
    N = line0[0]
    K = line0[1]
    ary = list(map(int,input().strip().split()))
    result = longestOnes(ary,K)
    print(result)

算法思路：双指针，滑动窗口