快排 QUICKSORT

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62

/* 分为4个区段 p<= k <= i,  arr[k] <= x i+1<= k <= j-1, arr[k] > x j< k < r, 待扫描 k = r, arr[k] = x */ function partition(arr, p, r){     var i = p - 1,         j = p,         x = arr[r];     while(j < r){         if(arr[j] <= x){             i = i + 1;             swap(arr, i, j);         }         j = j + 1;     }     swap(arr, r, i + 1);     return i + 1; }     function quicksort(arr, p, r){     if(p<r){         var q = partition(arr, p, r);         quicksort(arr, p, q-1);         quicksort(arr, q+1, r);     } }   function test(){     var arr = [8,9,6,3,5,11,16,2];     quicksort(arr, 0, arr.length-1);     print(arr);           arr = [6,6,6,6,6,6,6,6];     quicksort(arr, 0, arr.length-1);     print(arr);           arr = [1,2,3,4,5,6,7,8];     quicksort(arr, 0, arr.length-1);     print(arr);           arr = [8,7,6,5,4,3,2,1];     quicksort(arr, 0, arr.length-1);     print(arr); }   function print(arr){     var str = "";     arr.forEach(function(n, i){         str += " " + n;     });     console.log(str); }   function swap(arr, i, j){     var temp = arr[i];     arr[i] = arr[j];     arr[j] = temp; }