WAP to Concatenating the Two String while removing duplicate characters Efficiently

Given two strings s1 and s2, s1 has some characters at the end which are same as some of s2's starting characters, so you have to concatenate the strings so that the repeated portion occurs only once.

ex: S1="ABCDEFGHIJK"
S2="GHIJKXYZ"

OUTPUT="ABCDEFGHIJKXYZ"


#include
#include
int main()
{
char s1[] ="ABCDEFGHIJK";//"ABCDCDEF";
char s2[]="GHIJKXYZ";// "CDEFGHI";
char s3[100];
char *p1;
char *p2;
p1= s1;
p2 =s2;
int i =0;
while(*p1 )
{
if(*p1 != *p2)
{
s3[i++] = *p1;
p1++;

}
if(*p1 == *p2)
{
s3[i++] = *p1;
p1++;
p2++;
}

}
while(*p2)
{
s3[i++] = *p2;
p2++;
}
s3[i] = '\0';
printf("string is %s",s3);
getchar();
}

Run Here https://ideone.com/Y1yGb