russianDollEnvelopes.js

/**
 * @param {number[][]} envelopes
 * @return {number}
 */
var maxEnvelopes = function(envelopes) {
  // Edge Cases
  if ( envelopes === null || envelopes.length === 0) {
    return 0;
  }
  if ( envelopes.length === 1) {
    return 1;
  }

  envelopes = envelopes.slice().sort(function (a, b) {
    if (a[0] > b[0]) {
      return 1;
    }
    if (a[0] < b[0]) {
      return -1;
    }

    return a[1] - b[1];
  });

  var result = new Array(envelopes.length);
  var max = 1;
  var i, j;

  for (i = 0; i < envelopes.length; i++) {
    result[i] = 1;
    for (j = 0; j < i; j++) {
      if ( (envelopes[j][0] < envelopes[i][0]) && (envelopes[j][1] < envelopes[i][1])) {
        result[i] = Math.max(result[i], result[j] + 1); 
      }
    }
    if (max < result[i]) {
      max = result[i];
    }
  }

  return max; 
};