TheAlgorithms-C/LongestSubSequence.c

#include <stdio.h>
#include <stdlib.h>


void longestSub(int* ARRAY,int ARRAY_LENGTH, int** RESULT,int* RESULT_LENGTH){	//RESULT and RESULT_LENGTH will be modified by their pointers
	
	if(ARRAY_LENGTH <= 1){
		*RESULT=ARRAY;
		*RESULT_LENGTH = ARRAY_LENGTH;
	}
	else{
		int PIVOT = ARRAY[0];													
		int *LONGEST_SUB = NULL;														
		int i, j, LONGEST_SUB_LENGTH = 0;												
		int TEMPORARY_ARRAY_LENGTH = 0, *TEMPORARY_ARRAY = NULL;

		for(i = 1; i < ARRAY_LENGTH; i++){
			if (ARRAY[i] < PIVOT){
				
				TEMPORARY_ARRAY_LENGTH = 0;
				TEMPORARY_ARRAY = NULL;

				for(j = i+1;j < ARRAY_LENGTH; j++){
					if(ARRAY[j] >= ARRAY[i]){

						TEMPORARY_ARRAY_LENGTH++;
						TEMPORARY_ARRAY = (int *)realloc(TEMPORARY_ARRAY, TEMPORARY_ARRAY_LENGTH*sizeof(int));
						TEMPORARY_ARRAY[TEMPORARY_ARRAY_LENGTH-1] = ARRAY[j];
					}
				}

				longestSub(TEMPORARY_ARRAY, TEMPORARY_ARRAY_LENGTH, &TEMPORARY_ARRAY, &TEMPORARY_ARRAY_LENGTH);
				if(LONGEST_SUB_LENGTH < TEMPORARY_ARRAY_LENGTH + 1){

					LONGEST_SUB_LENGTH = TEMPORARY_ARRAY_LENGTH + 1;
					LONGEST_SUB = (int *)realloc(LONGEST_SUB, LONGEST_SUB_LENGTH*sizeof(int));
					LONGEST_SUB[0] = ARRAY[i];

					for(i = 1;i < LONGEST_SUB_LENGTH; i++)
						LONGEST_SUB[i] = TEMPORARY_ARRAY[i-1];	
				}
			}
		}

		TEMPORARY_ARRAY = NULL;
		TEMPORARY_ARRAY_LENGTH = 0;
		for(i = 1;i < ARRAY_LENGTH; i++){

			if(ARRAY[i] >= PIVOT){
				TEMPORARY_ARRAY_LENGTH++;
				TEMPORARY_ARRAY = (int *)realloc(TEMPORARY_ARRAY, TEMPORARY_ARRAY_LENGTH*sizeof(int));
				TEMPORARY_ARRAY[TEMPORARY_ARRAY_LENGTH-1] = ARRAY[i];
			}
		}

		longestSub(TEMPORARY_ARRAY, TEMPORARY_ARRAY_LENGTH, &TEMPORARY_ARRAY, &TEMPORARY_ARRAY_LENGTH);
		if(TEMPORARY_ARRAY_LENGTH + 1 > LONGEST_SUB_LENGTH){

			LONGEST_SUB_LENGTH = TEMPORARY_ARRAY_LENGTH + 1;
			LONGEST_SUB = (int *)realloc(LONGEST_SUB, LONGEST_SUB_LENGTH*sizeof(int));
			LONGEST_SUB[0] = PIVOT;
			for(i = 1;i < LONGEST_SUB_LENGTH; i++)
				LONGEST_SUB[i] = TEMPORARY_ARRAY[i-1];
		}
		*RESULT = LONGEST_SUB;
		*RESULT_LENGTH = LONGEST_SUB_LENGTH;
	}
	

}

int main(){

	int EXAMPLE_LENGTH = 8;
	int EXAMPLE[] = {18, 2, 15, 4, 30, 0, 11, 12};
	
	int *RESULT = NULL;
	int RESULT_LENGTH, i;
	
	longestSub(EXAMPLE, EXAMPLE_LENGTH, &RESULT, &RESULT_LENGTH);

	printf("Longest Sub Sequence length: %d and it's:\n", RESULT_LENGTH);
	for(i = 0;i < RESULT_LENGTH; i++)
		printf("%d ",RESULT[i]);
	printf("\n");

	return 0;
}