<p>Given a binary array <code>nums</code>, return <em>the maximum length of a contiguous subarray with an equal number of </em><code>0</code><em> and </em><code>1</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> nums = [0,1]
<strong>Output:</strong> 2
<strong>Explanation:</strong> [0, 1] is the longest contiguous subarray with an equal number of 0 and 1.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> nums = [0,1,0]
<strong>Output:</strong> 2
<strong>Explanation:</strong> [0, 1] (or [1, 0]) is a longest contiguous subarray with equal number of 0 and 1.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
	<li><code>nums[i]</code> is either <code>0</code> or <code>1</code>.</li>
</ul>

class Solution {
public:
    int findMaxLength(vector<int>& nums) {
        if (nums.size() == 1) return 0;
        int maxL = 0;
        int ranges[nums.size()];
        stack<int> odd, even;
        if (nums[0] == 0) even.push(0);
        else odd.push(0);
        ranges[0] = -1;
        for (int i = 1; i < nums.size(); i++) {
            ranges[i] = -1;
            if (nums[i] == 0) {
                even.push(i);
                if (odd.size() > 0) {
                    int key = odd.top() - 1, start = odd.top();
                    if (key >= 0 && ranges[key] != -1) {
                        start = ranges[key];
                        // ranges.erase(key);
                    }
                    ranges[i] = start;
                    odd.pop();
                }
            }
            else {
                odd.push(i);
                if (even.size() > 0) {
                    int key = even.top() - 1, start = even.top();
                    if (key >= 0 && ranges[key] != -1) {
                        start = ranges[key];
                        // ranges.erase(key);
                    }
                    ranges[i] = start;
                    even.pop();
                }
            }
            if (ranges[i] >= 0) {
                maxL = max(maxL, i - ranges[i] + 1);
            }
        }
        return maxL;
    }
};
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