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Java-based LeetCode algorithm problem solutions, regularly updated

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package g0501_0600.s0525_contiguous_array;

// #Medium #Array #Hash_Table #Prefix_Sum #2022_07_28_Time_31_ms_(80.05%)_Space_77.6_MB_(61.34%)

import java.util.HashMap;

/**
 * 525 - Contiguous Array\.
 *
 * Medium
 *
 * Given a binary array `nums`, return _the maximum length of a contiguous subarray with an equal number of_ `0` _and_ `1`.
 *
 * **Example 1:**
 *
 * **Input:** nums = [0,1]
 *
 * **Output:** 2
 *
 * **Explanation:** [0, 1] is the longest contiguous subarray with an equal number of 0 and 1.
 *
 * **Example 2:**
 *
 * **Input:** nums = [0,1,0]
 *
 * **Output:** 2
 *
 * **Explanation:** [0, 1] (or [1, 0]) is a longest contiguous subarray with equal number of 0 and 1.
 *
 * **Constraints:**
 *
 * *   1 <= nums.length <= 10⁵
 * *   `nums[i]` is either `0` or `1`.
**/
public class Solution {
    public int findMaxLength(int[] nums) {
        for (int i = 0; i < nums.length; i++) {
            if (nums[i] == 0) {
                nums[i] = -1;
            }
        }
        HashMap map = new HashMap<>();
        map.put(0, -1);
        int ps = 0;
        int len = 0;
        for (int i = 0; i < nums.length; i++) {
            ps += nums[i];
            if (!map.containsKey(ps)) {
                map.put(ps, i);
            } else {
                len = Math.max(len, i - map.get(ps));
            }
        }
        return len;
    }
}