165. Compare Version Numbers

比较版本号。将版本号按照点号分隔成修订号，从左到右进行比较。

• 时间复杂度O(m + n)，空间复杂度O(1)
• Runtime: 110 ms, faster than 12.69%
• Memory Usage: 37.9 MB, less than 97.76%

/**
 * @param {string} version1
 * @param {string} version2
 * @return {number}
 */
var compareVersion = function(version1, version2) { 
  const v1 = version1.split('.');
  const v2 = version2.split('.');
  for (let i = 0; i < v1.length || i < v2.length; i++) {
    x = i < v1.length ? parseInt(v1[i]) : 0;
    y = i < v2.length ? parseInt(v2[i]) : 0;
    if (x > y) {
      return 1;
    }
    if (x < y) {
      return -1;
    }
  }
  return 0;
};