mathball/lib/matrixChain/index.js

A JavaScript library for Competitive Programming

'use strict';

function _toConsumableArray(arr) { if (Array.isArray(arr)) { for (var i = 0, arr2 = Array(arr.length); i < arr.length; i++) { arr2[i] = arr[i]; } return arr2; } else { return Array.from(arr); } }

/*Matrix Chain Multiplication
*Function: M.matrixChain([])
*/

var validate = require('../validation/integer-array');

var matrixChain = function matrixChain(ar) {
	var n = ar.length;
	var m = [].concat(_toConsumableArray(Array(n))).map(function (x) {
		return Array(n).fill(0);
	});
	var cost = void 0,
	    j = void 0;

	for (var i = 0; i < n; i++) {
		m[i][i] = 0;
	}
	for (var l = 2; l < n; l++) {
		for (var _i = 1; _i < n - l + 1; _i++) {
			j = _i + l - 1;
			m[_i][j] = Number.MAX_SAFE_INTEGER;
			for (var k = _i; k <= j - 1; k++) {
				cost = m[_i][k] + m[k + 1][j] + ar[_i - 1] * ar[k] * ar[j];
				if (cost < m[_i][j]) {
					m[_i][j] = cost;
				}
			}
		}
	}
	return m[1][n - 1];
};

exports.matrixChain = function (arr) {
	validate(arr, 'matrixChain');
	return matrixChain(arr);
};