linked list inside a linked list segmentation error - c

Question

#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <stdbool.h>
struct smallnode{
char name[4];
struct smallnode *next;
};
struct bignode {
int no;
struct smallnode *element;
struct smallnode *ehead;
struct bignode *next;
};
struct bignode *classes;
struct bignode *head;
void add_class(int no){
struct bignode *newclass = malloc(sizeof(struct bignode));
newclass->no=no;
newclass->element=NULL;newclass->ehead=NULL;
if(head==NULL){classes = newclass;head = classes;head->next=NULL;}
else{
head->next=newclass;
head = head->next;
head->next=NULL;
}
}
void add_student(int noc,char* name){
struct bignode *pointer;
pointer = classes;
int i;
// get the desired class
for(i=2;i<=noc;i++){
pointer=pointer->next;
}
//add student to class
struct smallnode *newstud;
newstud = malloc(sizeof(struct smallnode));
strcpy(newstud->name,name);
if(pointer->element==NULL){
pointer->element=newstud;
pointer->ehead = pointer->element;
pointer->ehead->next=NULL;
}
else{
pointer->ehead->next=newstud;
pointer->ehead = pointer->ehead->next;
pointer->ehead->next=NULL;
}
}
void resetdata(){
struct bignode *classpointer;
struct bignode *t;
struct smallnode *studentpointer;
struct smallnode *c;
classpointer = classes;
while(classpointer!=NULL){
t=classpointer;
studentpointer=classpointer->element;
while(studentpointer!=NULL){
c = studentpointer;
studentpointer= studentpointer->next;
free(c);
}
classpointer=classpointer->next;
free(t);
}
classes = NULL;
head = NULL;
}
int main()
{
FILE *fp,*op;
int sclasw=0;int adstud=0; int noc=1;int cp=0; char c; char sname[4]=""; int sc=0;
int cases;
classes = NULL;
head = NULL;
fp = stdin;
op = stdout;
if (fp == NULL){
printf("null");
}
cases =fgetc(fp)-'0';
fgetc(fp);
//reading
int i;
for(i=1;i<=cases;i++){
c = fgetc(fp);
while(c!='\n'){
c = fgetc(fp);
if(c==':'){sclasw=1;}
else if (c=='('&&sclasw==0){adstud=1;}
else if (c=='('&&sclasw==1){}
else if (c==')'&&sclasw==1){sclasw=0;add_class(noc);}
else if (c==')'&&adstud==1){adstud=0;add_student(cp,sname);sc=0;}
else if (sclasw==1&&c==','){
add_class(noc);
noc++;
}
else if (c==','&&adstud==1){
add_student(cp,sname);
sc=0;
}
else if (c==','&&sclasw==0&&adstud==0){
cp++;sc=0;
}
else if(adstud==1){
sname[sc]=c;
sc++;
}else if(sclasw==1){/*printf("-");*/}
}
//end reading
//coloring algo
struct bignode *classpointer;
struct bignode *classpointer2;
struct smallnode *studentpointer;
struct smallnode *studentpointer2;
int *color, totalcolor;
color=malloc((noc+1)*sizeof(int));
color[1]=1; totalcolor = 1;
int col,oldcol;
//breaker
int b1=0,b2=0,b3=0;
classpointer = classes->next;
while(classpointer!=NULL){
for(col=1;col<=totalcolor;){
color[classpointer->no]=col;
oldcol=col;
studentpointer = classpointer->element;
while (studentpointer!=NULL){//for the nth element
classpointer2 = classes;
while(classpointer2!=classpointer){//check the class
if (color[classpointer2->no]==col){
studentpointer2 = classpointer2->element;
while (studentpointer2!=NULL){// for an element
if(strcmp(studentpointer->name,studentpointer2->name)==0){//that has the same student as the nth element
col++;//if theres the same student next color
color[classpointer->no]=col;
if(col>totalcolor){//if there is no next color create one
totalcolor++;b1=1;
}
b2=1;
b3=1;
break;
}
studentpointer2 = studentpointer2->next;
}
}
classpointer2=classpointer2->next;
if(b3==1){b3=0;break;}
}
studentpointer = studentpointer->next;
if(b2==1){b2=0;break;}
}
if (color[classpointer->no]==oldcol){break;}
if(b1==1){b1=0;break;}
}
classpointer=classpointer->next;
}
//end algo
fprintf(op,"Case %i: (",i);
classpointer=classes;
while(classpointer!=NULL){
fprintf(op,"C%02i:%i",classpointer->no,color[classpointer->no]);
classpointer=classpointer->next;
if(classpointer!=NULL)fprintf(op,", ");
}
fprintf(op,")\n");
resetdata();
sclasw = 0; adstud = 0; noc=1;cp=0;sc = 0;
}
return 0;
fclose(fp);
fclose(op);
}
//EDIT
Input:
1
Case 1: (C01,C02,C03,C04,C05,C06,C07,C08,C09,C10,C11),(RDA,ALB,NAC,EDF,BMG,VLJ,IVL,LGM,EGN,KSO,EST,VIV),(MCA,EDF,SLF,ADG,BCG,AAI,RRK,LGM,RLM,JGP,LRQ,WAR,KLS,DDY),(ABC,BBD,GCF,ADG,AKL,BCL,MIN,JGP,RSQ,DBU,IEY,RAW,ESZ),(ANA,JCA,CAB,NAC,GCF,GLH,VLJ,LLM,MAN,PEP,PQQ,ERR,SET,MAV,REW),(BBC,EDD,HSE,EST,ELG,ISH,JEI,EMJ,RRK,TPL,RER,EPS,AVU,CDW,ELY),(ALA,MCA,ABB,BCF,GLH,AKL,HGN,RON,JGP,ALQ,EPR,ABT,KEV,YEZ),(CDC,ISH,ABI,DHJ,ESM,FBM,RMN,PEP,VIR,JLS,LOT,MAV,TEX),(AAA,HLA,BBD,WRE,ECG,HLH,DHJ,RON,TSO,PQQ,MBT,REW,BAX,TRY,BDZ),(MCA,JCA,BCF,EGG,AAI,XTK,WIL,CSM,HLO,RSP,APR,RER,JET,DBU),(RDA,BBB,CLC,ECG,MNH,EMJ,JOK,ARM,NFM,EGN,RCN,RSP,LEQ,YIR,AVU),(ADB,WDB,BKC,CLC,SDE,UKF,BMG,HRH,BTK,LGM,QJP,EPS,KLS,BST,YNZ)
Output(in codeblocks which works just fine):
Case 1: (C01:1, C02:2, C03:1, C04:2, C05:3, C06:3, C07:1, C08:4, C09:4, C10:2, C11:4)
PS. I've already edited my source code such that there are no minor mistakes like insufficient memory for array.
This program does graph coloring by using 2 arrays. One for the classes and the other or student. The bigger linked list, which is the one for classes, has an element of a smaller linked list in each node;
Hackerrank's compiler says that it has a segmentation error, but it works fine when I run it in code blocks.
I've been stuck with this for days and I dont have any clue why this is happening. Please help me :(