迭代合并排序算法

 1 function merge(left, right) {

 2     var result = [];

 3 

 4     while (left.length > 0 && right.length > 0) {

 5         if (left[0] < right[0]) {

 6             result.push(left.shift());

 7         } else {

 8             result.push(right.shift());

 9         }

10     }

11     return result.concat(left).concat(right);

12 }

13 

14 function mergeSort(items) {

15     if (items.length == 1) {

16         return items;

17     }

18 

19     var work = [];

20     for (var i = 0, len = items.length; i < len; i++) {

21         work.push([items[i]]);

22     }

23     work.push([]); //如果数组长度为奇数

24     for (var lim = len; lim > 1; lim = (lim + 1) / 2) {

25         for (var j = 0, k = 0; k < lim; j++, k += 2) {

26             work[j] = merge(work[k], work[k + 1]);

27         }

28         work[j] = []; //如果数组长度为奇数

29     }

30     return work[0];

31 }