algs4js/dist/dynamic-programming/MaxSubArray.js

Basic algorithms and data structures implemented with es6

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});

var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();

var _LogUtil = require('../util/LogUtil');

var _LogUtil2 = _interopRequireDefault(_LogUtil);

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

/**
 * Class MaxSubArray
 *
 * Exposes static fucntionality for finding the maxium subarray sum through dynamic programming
 */
var MaxSubArray = function () {
  function MaxSubArray() {
    _classCallCheck(this, MaxSubArray);
  }

  _createClass(MaxSubArray, null, [{
    key: 'find',


    /**
     * Finds the maximum subarray for a given array.  Uses the following dynamic programming
     * algorithm:
     *
     * S(0) = A(0);
     * S(i) = max(S(i-i) + A(i), A(i))
     *
     * @param {number[]} the input array of numbers
     * @returns {number} the maxium subarray sum
     */
    value: function find(arr) {
      _LogUtil2.default.debug('Finding max of arr ' + arr);
      if (!Array.isArray(arr) || arr.length === 0) {
        return null;
      }
      var sum = [arr[0]];
      for (var i = 1; i < arr.length; i++) {
        sum[i] = Math.max(sum[i - 1] + arr[i], arr[i]);
      }
      _LogUtil2.default.debug('Resulting S[i]: ' + sum);
      var maxSum = Math.max.apply(Math, sum);
      _LogUtil2.default.debug('Found max sum to be: ' + maxSum);
      return maxSum;
    }
  }]);

  return MaxSubArray;
}();

exports.default = MaxSubArray;