Segmentation fault in HackerRank C program - c

Question

This is the challenge I'm trying to solve:
https://www.hackerrank.com/challenges/querying-the-document/
So far I have made progress but I am stuck at a Segmentation Fault and I can't figure out why.
The following is an abridged version of the whole source code:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
char**** get_document(char* text) {
int spaces = 0, periods = 0, newlines = 0;
for(int i = 0; i != strlen(text); i++) {
if(text[i] == ' ')
spaces++;
else if(text[i] == '.')
periods++;
else if(text[i] == '\n')
newlines++;
}
char** para[periods + 1]; // each paragraph stores that many sentences
char* senten[spaces + 1]; // each sentence stores that many words
char*** doc[newlines + 1]; // each document stores that many paragraphs
int start = 0, k = 0, m, p = 0, x = 0;
for(int i = 0; i != strlen(text); i++) {
if(text[i] == ' ' || text[i] == '.') { // space or period means there was a word before it
senten[k] = (char*) malloc(sizeof(char) * (i - start)); // store each word
m = 0;
for(int j = start; j < i; )
senten[k][m++] = text[j++];
senten[k][m++] = '\0'; // append a '\0' to end the string
if(text[i + 1] == '\n') { // newline means that a new paragraph is starting
para[p] = senten; // store pointer to sentence in para
while(k)
senten[k--] = NULL; // don't need now
start = i + 2;
p++;
}
else
start = i + 1;
k++;
}
if(i == strlen(text) - 1) { // end of file
doc[x++] = para; // store pointer to paragraph in doc
while(p)
para[p--] = NULL; // don't need
}
}
return doc;
}
int main()
{
char* text = "Hello World.\nHi.Bye.";
char**** doc = get_document(text);
printf("%s",doc[0][0][0]); // should print "Hello"
return 0;
}
In short the program is supposed to take a char* and output a char****.
Example:
If char * text = "Hello World.\nHi.Bye.";
Then char **** doc = {{{"Hello","World"}},{{"Hi"},{"Bye"}}};

Answer 1

You return the local variable in get_document function:
char** para[periods + 1]; // each paragraph stores that many sentences
char* senten[spaces + 1];
char*** doc[newlines + 1];
...
return doc;
It's bad idea, Because out of get_document function, the variable doc maybe does not exist.
You should use:
char*** para = malloc((periods + 1) * sizeof(char **));
char** senten = malloc((spaces + 1) * sizeof(char *));
char**** doc = malloc((newlines + 1)*sizeof(char ***));

Answer 2

This is how I modified my code. Now it passes all the test cases.
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
char**** get_document(char* newtext) {
int spaces = 0, periods = 0, newlines = 0;
for(int i = 0; i != strlen(newtext); i++) {
if(newtext[i] == ' ')
spaces++;
else if(newtext[i] == '.')
periods++;
else if(newtext[i] == '\n')
newlines++;
}
char*** para = malloc((periods + 1) * sizeof(char **));
char** senten = malloc((spaces + 1) * sizeof(char *));
char**** doc = malloc((newlines + 1) * sizeof(char ***));
int start = 0, k = 0, m, p = 0, x = 0, f = 0, pp = 0;
int pcount = 0;
for(int i = 0; i != strlen(newtext); i++) {
if(newtext[i] == '.') pcount++;
if(newtext[i] == ' ' || newtext[i] == '.') { // space or period means there was a word before it
senten[k] = (char*) malloc(sizeof(char) * (i - start) + 1); // store each word
m = 0;
for(int j = start; j < i; )
senten[k][m++] = newtext[j++];
senten[k][m++] = '\0'; // append a '\0' to end the string
k++;
if(i != strlen(newtext) && newtext[i + 1] == '\n') // newline means that a new paragraph is starting
start = i + 2;
else
start = i + 1;
if(i != strlen(newtext) && isalpha(newtext[i + 1]) && newtext[i] == '.') {
para[p++] = senten;
senten = malloc((spaces + 1) * sizeof(char *));
k = 0;
}
if((i != strlen(newtext) && newtext[i + 1] == '\n') || i + 1 == strlen(newtext)) {
para[p++] = senten;
senten = malloc((spaces + 1) * sizeof(char *));
k = 0;
doc[f++] = &(para[pp]);
pp += pcount;
pcount = 0;
}
}
}
return doc;
}
int main()
{
char* newtext = "Hello World.\nHi.Bye.\nWow.";
char**** doc = get_document(newtext);
printf("%s\n", doc[0][0][0]);
printf("%s\n", doc[0][0][1]);
printf("%s\n", doc[1][0][0]);
printf("%s\n", doc[1][1][0]);
printf("%s\n", doc[2][0][0]);
return 0;
}