寻找数组中的第K个最大的数

  1 #include                                                                                   
  2
  3 using namespace std;
  4
  5 int Partition(int *l,int low,int high)
  6 {
  7     int temp = l[low];
  8     int pt = l[low];
  9
 10     while(low < high)
 11     {
 12         while(low < high && l[high] >= pt)
 13             --high;
 14         l[low] = l[high];
 15         while(low < high && l[low] <= pt)
 16             ++low;
 17         l[low] = temp;
 18     }
 19     l[low] = temp;
 20     return low;
 21 }
 22
 23 void Qsort(int *l,int low,int high)
 24 {
 25     if(low < high)
 26     {
 27         int pl = Partition(l,low,high);
 28         Qsort(l,low,pl - 1);
 29         Qsort(l,pl + 1,high);
 30     }
 31 }
 32
 33 int main(void)
 34 {
 35     int narry[100],addr[100];   /* 定义数组*/
 36     int sum = 1,t;              /* sum为数组的下标 */
 37
 38     cout << "Input number:"<< endl; /* 接收输入的数，为－1时将不再输出*/
 39     cin >> t;
 40
 41     while(t != -1)
 42     {
 43         narry[sum] = t;     /*该数组下标从1开始 */
 44         addr[sum - 1] = t;  /*该数组下标从0开始 */
 45         sum++;
 46         cin >> t;
 47     }
 48
 49     sum -= 1;               /* sum 为当前数组的元素个数*/
 50     Qsort(narry,1,sum); 
 51
 52     for(int i = 1; i <= sum;i++)
 53         cout << narry[i] << '\t';
 54         cout << endl;
 55
   56     int k;
 57     cout <<"please input place you want:"< 58     cin >>k;
 59
 60     int aa = 1;
 61     int kk = 0;
 62     for(;;)
 63     {
 64         if(aa == k)
 65             break;
 66         if(narry[kk] != narry[kk + 1])
 67         {
 68             aa += 1;
 69             kk++;
 70         }
 71     }
 72
 73     cout << "The NO." << k << "number is :" << narry[sum - kk] << endl;
 74   return 0;}                                                                                                   


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