525. Contiguous Array
Given a binary array, find the maximum length of a contiguous subarray with equal number of 0 and 1.
Example 1:
Input: [0,1] Output: 2 Explanation: [0, 1] is the longest contiguous subarray with equal number of 0 and 1.
Example 2:
Input: [0,1,0] Output: 2 Explanation: [0, 1] (or [1, 0]) is a longest contiguous subarray with equal number of 0 and 1.
Note: The length of the given binary array will not exceed 50,00
class Solution { public: //hash表。o(N)的时间复杂度 //0 1 0 1 0 0 1 1 //可以这样考虑 每次遇到0。count就减1,每次遇到1count就加1 //这样,当往后扫描时,下一次再遇到这个count时,这两个位置之间的0和1就是相等的 int findMaxLength(vector<int>& nums) { map<int,int> m; int count = 0, res=0; m[count] = 0; for(int i=0;i<nums.size();i++){ if(nums[i] == 0){ count--; }else{ count++; } if(m.find(count) != m.end()){ res = max(res,i+1 - m[count]); }else{ m[count] = i+1; } } return res; } };