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 50,000.
题意,统计最长的子序列,其中0和1的个数相同,
统计每个位子的和,把0看做-1即可
class Solution { public int findMaxLength(int[] nums) { Map<Integer, Integer> map = new HashMap<>(); map.put(0, -1); int sum = 0; int max = 0; for (int i = 0; i < nums.length; i++) { if (nums[i] == 0) nums[i] = -1; sum += nums[i]; if (map.containsKey(sum)) { max = Math.max(max, i - map.get(sum)); } else { map.put(sum, i); } } return max; } }