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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <string.h>
  4. #include <time.h>
  5.  
  6. char* input = "FourscoreandsevenyearsagoourfaathersbroughtforthonthiscontainentanewnationconceivedinzLibertyanddedicatedtothepropositionthatallmenarecreatedequalNowweareengagedinagreahtcivilwartestingwhetherthatnaptionoranynartionsoconceivedandsodedicatedcanlongendureWeareqmetonagreatbattlefiemldoftzhatwarWehavecometodedicpateaportionofthatfieldasafinalrestingplaceforthosewhoheregavetheirlivesthatthatnationmightliveItisaltogetherfangandproperthatweshoulddothisButinalargersensewecannotdedicatewecannotconsecratewecannothallowthisgroundThebravelmenlivinganddeadwhostruggledherehaveconsecrateditfaraboveourpoorponwertoaddordetractTgheworldadswfilllittlenotlenorlongrememberwhatwesayherebutitcanneverforgetwhattheydidhereItisforusthelivingrathertobededicatedheretotheulnfinishedworkwhichtheywhofoughtherehavethusfarsonoblyadvancedItisratherforustobeherededicatedtothegreattdafskremainingbeforeusthatfromthesehonoreddeadwetakeincreaseddevotiontothatcauseforwhichtheygavethelastpfullmeasureofdevotionthatweherehighlyresolvethatthesedeadshallnothavediedinvainthatthisnationunsderGodshallhaveanewbirthoffreedomandthatgovernmentofthepeoplebythepeopleforthepeopleshallnotperishfromtheearth";
  7.  
  8. char* sub_seq(const char* source, int start, int end)
  9. {
  10.     char* result;
  11. 	int i;
  12. 	result = malloc((end - start + 1) * sizeof(char));
  13. 	for (i = 0; i < end - start; ++i)
  14. 	{
  15. 		result[i] = source[i + start];
  16.  	}
  17.  	result[end - start] = '\0';
  18.  	return result;
  19. }
  20.  
  21. char* seek_palindrome(const char* input)
  22. {
  23. 	char* answer;
  24. 	answer = malloc(sizeof(char));
  25. 	answer[0] = '\0';
  26.  
  27. 	int len, i, j, k;
  28. 	len = strlen(input);
  29.  
  30. 	for (i = 1; i < len - 1; ++i)
  31. 	{
  32. 		for (j = i - 1, k = i + 1; j >= 0 && k < len; --j, ++k)
  33. 		{
  34. 			if (input[j] == input[k])
  35. 			{
  36. 				char* palindrome = sub_seq(input, j, k + 1);
  37. 				if (strlen(palindrome) > strlen(answer))
  38. 				{
  39. 					free(answer); answer = NULL;
  40. 					answer = palindrome;
  41. 				}
  42. 				else
  43. 				{
  44. 					free(palindrome);
  45. 				}
  46. 			}
  47. 			else
  48. 			{
  49. 				break;
  50. 			}
  51. 		}
  52. 	}
  53.  
  54. 	for (i = 1; i < len - 1; ++i)
  55. 	{
  56. 		for (j = i, k = i + 1; j >= 0 && k < len; --j, ++k)
  57. 		{
  58. 			if (input[j] == input[k])
  59. 			{
  60. 				char* palindrome = sub_seq(input, j, k + 1);
  61. 				if (strlen(palindrome) > strlen(answer))
  62. 				{
  63. 					free(answer); answer = NULL;
  64. 					answer = palindrome;
  65. 				}
  66. 				else
  67. 				{
  68. 					free(palindrome);
  69. 				}
  70. 			}
  71. 			else
  72. 			{
  73. 				break;
  74. 			}
  75. 		}
  76. 	}
  77. 	return answer;
  78. }
  79.  
  80. int main(int argc, char* argv[])
  81. {
  82. 	clock_t t;
  83. 	char* result;
  84. 	t = clock();
  85. 	result = seek_palindrome(input);
  86. 	t = clock() - t;
  87.  
  88. 	printf("The longest palindrome is '%s' calculated in %f seconds\n", result, ((float) t) / CLOCKS_PER_SEC);
  89. 	free(result); result = NULL;
  90. 	return EXIT_SUCCESS;
  91. }
Success #stdin #stdout 0s 1964KB
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stdin
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Standard input is empty
stdout
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The longest palindrome is 'ranynar' calculated in 0.000000 seconds
https://ideone.com/lKQ0Ca
language:
C (gcc 8.3)
created:
13 years ago
visibility:
public

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