Contiguous Array问题及解法

问题描述：

Given a binary array, find the maximum length of a contiguous subarray with equal number of 0 and 1.

示例:

Input: [0,1]Output: 2Explanation: [0, 1] is the longest contiguous subarray with equal number of 0 and 1.

Input: [0,1,0]Output: 2Explanation: [0, 1] (or [1, 0]) is a longest contiguous subarray with equal number of 0 and 1.

问题分析：

这里我们重点看的是连续子数组0和1的数目zero和one，遍历时我们把zero - one 和 i 存储起来，若后续子数组中0的数目和1的数目相等，那么zero - one的值就会被检测到出现过一次，然后得到子数组的长度，最终比较得到更长的长度。

过程详见代码：

class Solution {public:    int findMaxLength(vector<int>& nums) {        int res = 0,n = nums.size();int zero = 0, one = 0;unordered_map<int, int> map;map[0] = -1;for (int i = 0; i < n; i++){if (nums[i] == 0) zero++;else one++;if (map.find(zero - one) != map.end()){res = max(res, i - map[zero - one]);}else map[zero - one] = i;}return res;    }};