15、中间数

 1 #include<stdio.h>
 2 void sort(int *number, int n){
 3      int i, j, k,temp;
 4      for (i = 0; i < n - 1; i++){
 5            k = i;
 6            for (j = i + 1; j < n; j++){
 7                 if (*(number + j) < *(number + k))
 8                      k = j;
 9            }
10            temp = *(number + k);
11            *(number + k) = *(number + i);
12            *(number + i) = temp;
13      }
14 }
15 
16 int main(){
17      int n,i,j,num[1000];
18      scanf("%d", &n);
19      for (i = 0; i < n; i++)
20            scanf("%d", &num[i]);
21      sort(num, n);
22      int low, high,middle,flag;
23      low = high =flag= 0;
24      middle = (n - 1) / 2;
25      if (n % 2 == 1){
26            for (j = 0; j < middle; j++){
27                 if (num[j] != num[middle])
28                      low++;
29            }
30            for (j = middle + 1; j < n; j++){
31                 if (num[j] != num[middle])
32                      high++;
33            }
34            if (low == high)
35                 flag = 1;
36      }
37      else{
38            if (num[middle] == num[middle + 1]){
39                 for (j = 0; j < middle; j++){
40                      if (num[j] != num[middle])
41                            low++;
42                 }
43                 for (j = middle + 2; j < n; j++){
44                      if (num[j] != num[middle])
45                            high++;
46                 }
47                 if (low == high)
48                      flag = 1;
49            }
50      }
51      if (flag == 1)
52            printf("%d\n", num[middle]);
53      else
54            printf("-1\n");
55      return 0;
56 }