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  1. #include <stdio.h>
  2.  
  3. int binary_search(int a[], int n, int x) {
  4.     int left = 0;
  5.     int right = n - 1;
  6.  
  7.     while (left <= right) {
  8.         int mid = (left + right) / 2;
  9.  
  10.         if (a[mid] == x) {
  11.             return mid;      
  12.         } else if (a[mid] < x) {
  13.             left = mid + 1;  
  14.         } else {
  15.             right = mid - 1; 
  16.         }
  17.     }
  18.     return -1; 
  19. }
  20.  
  21. int main(void) {
  22.     int n, x;
  23.     int a[100000];
  24.  
  25.     scanf("%d %d", &n, &x);
  26.     for (int i = 0; i < n; i++) {
  27.         scanf("%d", &a[i]);
  28.     }
  29.  
  30.     int ans = binary_search(a, n, x);
  31.  
  32.     if (ans != -1) {
  33.         printf("a[%d] = %d\n", ans, x);
  34.     } else {
  35.         printf("not found\n");
  36.     }
  37.  
  38.     return 0;
  39. }
Success #stdin #stdout 0.01s 5320KB
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https://ideone.com/hzYDco
language:
C (gcc 8.3)
created:
1 day ago
visibility:
public

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