巧妙利用快速排序法的原理求一个数组中的第10大元素

//快速排序法int QuickSort_process3(int *a, int low, int high){int l, h, temp;l = low;h = high;temp = a[low];while (l < h){while (l< h&&a[h] >= temp)--h;if (l < h)a[l] = a[h];while (l < h&&a[l] < temp)++l;if (l < h)a[h] = a[l];}a[h] = temp;return h;}void QuickSort3(int *a, int low,int high){int pos;if (low < high){pos = QuickSort_process3(a,low,high);QuickSort3(a,low,pos-1);QuickSort3(a,pos+1,high);}}int getTop_N_Numbers(int *a,int n){int pos, curpos, e;do{printf("Please input a numbers(less than %d and bigger than 0).\n", n);scanf("%d",&e);} while (!(e<=n&&e>=1));pos = n - e;/*在一个从小到大排序的数组中，最大第e个数的下标恰好是n-e*/curpos = QuickSort_process3(a, 0, n - 1);/*一趟快排结束时，肯定会有一个已经确定了位置的数，返回它的下标*/while (1){if (curpos == pos){/*当要找的第几最大的数的位子已经确定后，说明，比它还要大的数也已经确定了，就不再排序了，直接返回*/break;}else if (curpos < pos){/*在后半部找*/curpos = QuickSort_process3(a,curpos+1,n-1);}else{/*在前半部分找*/curpos = QuickSort_process3(a,0,curpos-1);}}return pos;}void show_TopN_numbers(int *a,int n){int k = getTop_N_Numbers(a, n);int i;printf("The Top %d numbers are :\n",n-k);for (i = k; i < n; ++i)printf("%d ",a[i]);printf("\n");}