contiguous-array.js

/**
 * Max Contiguous Array with Equal Number of 0 and 1
 *
 * 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.
 */

/**
 * @param {number[]} nums
 * @return {number}
 */
const findMaxLength = nums => {
  const map = new Map([[0, -1]]);

  let result = 0;
  let sum = 0;

  for (let i = 0; i < nums.length; i++) {
    sum += nums[i] === 1 ? 1 : -1;

    if (map.has(sum)) {
      result = Math.max(result, i - map.get(sum));
    } else {
      map.set(sum, i);
    }
  }

  return result;
};

export { findMaxLength };