# The problem of “Arrays: Left Rotation” – C Source code

T

A left rotation operation on an array shifts each of the array’s elements 1 unit to the left. For example, if 2 left rotations are performed on array [1,2,3,4,5], then the array would become [3,4,5,1,2].

Given an array a of n integers and a number, d, perform d left rotations on the array. Return the updated array to be printed as a single line of space-separated integers.

https://www.hackerrank.com/challenges/array-left-rotation/problem

``````#include <assert.h>
#include <limits.h>
#include <math.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char** split_string(char*);

// Complete the rotLeft function below.

// Please store the size of the integer array to be returned in result_count pointer. For example,
// int a[3] = {1, 2, 3};
//
// *result_count = 3;
//
// return a;
//

int* rotLeft(int a_count, int* a, int d, int* result_count)
{
int* tmp = (int*)malloc(a_count * sizeof(int));

memmove(tmp, &a[d], (a_count - d) * sizeof(int));
memmove(&tmp[a_count - d], a, d * sizeof(int));
*result_count = a_count;

return tmp;
}

int main()
{
FILE* fptr = fopen(getenv("OUTPUT_PATH"), "w");

char* n_endptr;
char* n_str = nd[0];
int n = strtol(n_str, &n_endptr, 10);

if (n_endptr == n_str || *n_endptr != '\0') { exit(EXIT_FAILURE); }

char* d_endptr;
char* d_str = nd[1];
int d = strtol(d_str, &d_endptr, 10);

if (d_endptr == d_str || *d_endptr != '\0') { exit(EXIT_FAILURE); }

int* a = malloc(n * sizeof(int));

for (int i = 0; i < n; i++) {
char* a_item_endptr;
char* a_item_str = *(a_temp + i);
int a_item = strtol(a_item_str, &a_item_endptr, 10);

if (a_item_endptr == a_item_str || *a_item_endptr != '\0') { exit(EXIT_FAILURE); }

*(a + i) = a_item;
}

int a_count = n;

int result_count;
int* result = rotLeft(a_count, a, d, &result_count);

for (int i = 0; i < result_count; i++) {
fprintf(fptr, "%d", *(result + i));

if (i != result_count - 1) {
fprintf(fptr, " ");
}
}

fprintf(fptr, "\n");

fclose(fptr);

return 0;
}

size_t alloc_length = 1024;
size_t data_length = 0;
char* data = malloc(alloc_length);

while (true) {
char* cursor = data + data_length;
char* line = fgets(cursor, alloc_length - data_length, stdin);

if (!line) {
break;
}

data_length += strlen(cursor);

if (data_length < alloc_length - 1 || data[data_length - 1] == '\n') {
break;
}

alloc_length <<= 1;

data = realloc(data, alloc_length);

if (!line) {
break;
}
}

if (data[data_length - 1] == '\n') {
data[data_length - 1] = '\0';

data = realloc(data, data_length);
} else {
data = realloc(data, data_length + 1);

data[data_length] = '\0';
}

return data;
}

char** split_string(char* str) {
char** splits = NULL;
char* token = strtok(str, " ");

int spaces = 0;

while (token) {
splits = realloc(splits, sizeof(char*) * ++spaces);

if (!splits) {
return splits;
}

splits[spaces - 1] = token;

token = strtok(NULL, " ");
}

return splits;
}``````