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 50,000.
Solutions
class Solution {
public int findMaxLength(int[] nums) {
int res = 0, sum = 0;
HashMap<Integer, Integer> index = new HashMap<Integer, Integer>();
index.put(0, -1);
for (int i = 0; i < nums.length; i ++) {
if (nums[i] == 1) {
sum ++;
}
else {
sum --;
}
if (index.containsKey(sum)) {
res = Math.max(res, i - index.get(sum));
} else {
index.put(sum, i);
}
}
return res;
}
}