My C code won't stop taking in inputs using scanf function - c

Question

This is my first semester learning C and I have trouble with one of my homeworks.
It's a program to receive the lists of homework as sets of (t,d) and to evaluate the urgency of each homework. (t means time left until deadline and d mean difficulty.) The task is to sort the list primarily by the order of remaining time and if the remaining time is equal, to sort it by difficulty.
This code works perfectly well when the input is something like
(1,0), (2, 1), (4,5) ...
But when the input is like
(1,0), (1, 4), (2, 1)...
it won't stop receiving inputs. This happens when the 'time' of the homework is the same (or so I think). I can't figure out why it's doing this.
#include <stdio.h>
#define MAX 1024
void insertionSort(int a[], int b[], int num);
void printArray(int a[], int b[], int num);
int main()
{
int a[MAX] = {0};
int b[MAX] = {0};
int i, num;
scanf("%d", &num);
for(i=0; i<num; i++){
scanf("%d", &a[i]);
scanf("%d", &b[i]);
}
insertionSort(a, b, num);
return 1;
}
void insertionSort(int a[], int b[], int num)
{
int i, j, val, val2;
for(i=1; i<num; i++)
{
val = a[i];
val2 = b[i];
j = i-1;
while((j>=0) && (a[j]>=val))
{
if(a[j] == val){
if(val2 < b[j]){
a[j+1] = a[j];
b[j+1] = b[j];
j--;
}
}
else{
a[j+1] = a[j];
b[j+1] = b[j];
j--;
}
a[j+1] = val;
b[j+1] = val2;
}
}
printArray(a, b, num);
}
void printArray(int a[], int b[], int num)
{
int i;
for(i=0; i<num; i++){
printf("%d ", a[i]);
printf("%d", b[i]);
printf("\n");
}
}

Answer 1

Your code is not continuously receiving inputs, instead it is stuck in an infinite loop inside the insertionSort function
You just need to add an else case and break the loop.
Here is the working code:
#include <stdio.h>
#define MAX 1024
void insertionSort(int a[], int b[], int num);
void printArray(int a[], int b[], int num);
int main()
{
int a[MAX] = {0};
int b[MAX] = {0};
int i, num;
scanf("%d", &num);
for(i=0; i<num; i++)
{
scanf("%d", &a[i]);
scanf("%d", &b[i]);
}
insertionSort(a, b, num);
return 1;
}
void insertionSort(int a[], int b[], int num)
{
int i, j, val, val2;
for(i=1; i<num; i++)
{
val = a[i];
val2 = b[i];
j = i-1;
while((j>=0) && (a[j]>=val))
{
if(a[j] == val)
{
if(val2 < b[j])
{
a[j+1] = a[j];
b[j+1] = b[j];
j--;
}
else
{
break;
}
}
else
{
a[j+1] = a[j];
b[j+1] = b[j];
j--;
}
a[j+1] = val;
b[j+1] = val2;
}
}
printArray(a, b, num);
}
void printArray(int a[], int b[], int num)
{
int i;
for(i=0; i<num; i++)
{
printf("%d ", a[i]);
printf("%d", b[i]);
printf("\n");
}
}