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  1. #include <stdio.h>
  2.  
  3. int rev(int n) {
  4.     int dig,rev=0;
  5.     while(n>0)
  6.     {
  7.     	dig=n%10;
  8. 		rev=rev*10+dig;
  9. 		n/=10;
  10.     }
  11. 	return rev;
  12. }
  13.  
  14. int bins(int pr[],int e) { 
  15. 	int start=0,end=113,mid,flag=0;
  16. 	while(start<end) {
  17. 		mid=(start+end)/2;
  18. 		if(e>pr[mid]) {
  19. 			start=mid+1;
  20. 			printf("l");
  21. 		} else if(e<pr[mid]) { 
  22. 			end=mid-1;
  23. 			printf("o");
  24. 		} else if(e==pr[mid]) {
  25. 			flag=1;
  26. 			break;
  27. 		}
  28. 	}
  29. 	if (flag==1)
  30. 		return mid;
  31. 	else
  32. 		return 0;
  33. }
  34.  
  35. int main() {
  36. 	int j,i,N,revn,count,pr[]={2,3,5,7,11,101,131,151,181,
  37. 		191,313,353,373,383,727,757,787,797,919,
  38. 		929,10301,10501,10601,11311,11411,12421,12721,12821,13331,
  39. 		13831,13931,14341,14741,15451,15551,16061,16361,16561,16661,
  40. 		17471,17971,18181,18481,19391,19891,19991,30103,30203,30403,
  41. 		30703,30803,31013,31513,32323,32423,33533,34543,34843,35053,
  42. 		35153,35353,35753,36263,36563,37273,37573,38083,38183,38783,
  43. 		39293,70207,70507,70607,71317,71917,72227,72727,73037,73237,
  44. 		73637,74047,74747,75557,76367,76667,77377,77477,77977,78487,
  45. 		78787,78887,79397,79697,79997,90709,91019,93139,93239,93739,
  46. 		94049,94349,94649,94849,94949,95959,96269,96469,96769,97379,
  47. 		97579,97879,98389,98689,1003001};
  48.  
  49. 	scanf("%d",&N);
  50. 	if(N%2==0)
  51. 	N--;
  52. 	for(i=N;;i+=2) {
  53. 		revn=rev(i);
  54. 		if(i==revn) {
  55. 			printf("\n%d",revn);
  56. 			count=bins(pr,i);
  57. 			if(count!=0)
  58. 				break;
  59.         }
  60.    }
  61. 	printf("\n%d",i);
  62. 	return 0;
  63. }
Success #stdin #stdout 0.01s 2684KB
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https://ideone.com/5GBnce
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
secret

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