Question Definition
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.
Java Solution
public int findMaxLength(int[] nums) {
int res = 0, n = nums.length, sum = 0;
Map<Integer, Integer> m = new HashMap<>();
m.put(0, -1);
for (int i = 0; i < n; ++i) {
sum += (nums[i] == 1) ? 1 : -1;
if (m.containsKey(sum)) {
res = Math.max(res, i - m.get(sum));
} else {
m.put(sum, i);
}
}
return res;
}
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