Given two strings s1 and s2, merge them into one string by overlapping the suffix of the first string and the prefix of the second string. If there's nothing to concatenate, return the concatenation of the strings.

singkatan.cpp

#define x substr
auto singkatan(auto w, auto q) {
    int a=w.length(),b=q.length(),m=a<b?a:b;
    while(m--)if(w.x(a-m-1,m+1)==q.x(0,m+1))q=q.x(m+1,b-m);
    return w+q;
}