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  1. #include <stdio.h>
  2.  
  3. int BinarySearch(double *vals, int size, double ref);
  4.  
  5. int main(void) {
  6. 	// list to be searched (sorted)
  7. 	double vals[] = { 2.718, 3.14, 6.022, 10.23 };
  8. 	int size = sizeof(vals)/sizeof(vals[0]);
  9.  
  10.     // list where each value is searched
  11. 	double chks[] = { 2.0, 3.13, 3.14, 3.15, 15.0 };
  12. 	int num = sizeof(chks)/sizeof(chks[0]);
  13.  
  14. 	for(int idx=0; idx<num; idx++) {
  15. 		int pos = BinarySearch(vals, size, chks[idx]);
  16. 		if (pos >= 0) {
  17. 			printf("pos = %d, %f for %f\n", pos, vals[pos], chks[idx]);
  18. 		} else {
  19. 			printf("not found for %f\n", chks[idx]);
  20. 		}
  21. 	}
  22. 	return 0;
  23. }
  24.  
  25. int BinarySearch(double *vals, int size, double target) {
  26. 	int start = 0;
  27. 	int end = size - 1;
  28. 	int mid;
  29.  
  30. 	if (target < vals[start] || target > vals[end]) {
  31. 		return -1;
  32. 	}
  33.  
  34. 	while (start <= end) {
  35. 		mid = (start + end) / 2;
  36. 		if (mid == (start+1) && (target >= vals[start]) && (target < vals[mid])) {
  37. 			return start;
  38. 		} else if (target < vals[mid]) {
  39. 			end = mid - 1;
  40. 		} else {
  41. 			start = mid + 1;
  42. 		}
  43. 	}
  44.  
  45. 	if (end < start) {
  46. 		return end;
  47. 	}
  48. 	return start;
  49. }
  50.  
  51.  
Success #stdin #stdout 0s 9424KB
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stdin
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Standard input is empty
stdout
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not found for 2.000000
pos = 0, 2.718000 for 3.130000
pos = 1, 3.140000 for 3.140000
pos = 1, 3.140000 for 3.150000
not found for 15.000000
https://ideone.com/BFUgOE
C > algorithm > find nearest double value in array
language:
C (gcc 8.3)
created:
5 years ago
visibility:
public

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