[LeetCode] 1004. Max Consecutive Ones III

Given an array A of 0s and 1s, we may change up to K values from 0 to 1.

Return the length of the longest (contiguous) subarray that contains only 1s. 

Example 1:

Input: A = [1,1,1,0,0,0,1,1,1,1,0], K = 2
Output: 6
Explanation: 
[1,1,1,0,0,1,1,1,1,1,1]
Bolded numbers were flipped from 0 to 1.  The longest subarray is underlined.

Example 2:

Input: A = [0,0,1,1,0,0,1,1,1,0,1,1,0,0,0,1,1,1,1], K = 3
Output: 10
Explanation: 
[0,0,1,1,1,1,1,1,1,1,1,1,0,0,0,1,1,1,1]
Bolded numbers were flipped from 0 to 1.  The longest subarray is underlined.

Note:

1. 1 <= A.length <= 20000
2. 0 <= K <= A.length
3. A[i] is 0 or 1 

最大连续1的个数 III。

给定一个由若干 0 和 1 组成的数组 A，我们最多可以将 K 个值从 0 变成 1 。返回仅包含 1 的最长（连续）子数组的长度。

这是一道比较典型的滑动窗口类型的题目，我们可以直接套用76题的模板。

时间O(n)

空间O(1)

Java实现

class Solution {
    public int longestOnes(int[] A, int K) {
        int start = 0;
        int end = 0;
        int count = 0;
        int res = 0;
        while (end < A.length) {
            if (A[end] == 0) {
                count++;
            }
            // K用完了的时候就要开始缩减窗口范围
            while (count > K) {
                if (A[start] == 0) {
                    count--;
                }
                start++;
            }
            // 计算窗口大小
            res = Math.max(res, end - start + 1);
            end++;
        }
        return res;
    }
}

LeetCode中有如下一些题目，求的是连续出现的数字或者字母最长可以组成的子串长度，本质上还是滑动窗口类型的题目。

485. Max Consecutive Ones

487. Max Consecutive Ones II

1004. Max Consecutive Ones III

830. Positions of Large Groups

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