Z function

• https://cp-algorithms.com/string/z-function.html

template<class T> 
vector<T> z_function(const vector<T>& s){
	int n=sz(s);
	vector<T> z(n);
	for(int i=1,l=0,r=0;i<n;++i){
		if(i<=r) z[i]=min(r-i+1,z[i-l]);
		while(i+z[i]<n&&s[z[i]]==s[i+z[i]]) ++z[i];
		if(i+z[i]-1>r)
			l=i,r=i+z[i]-1;
	}
	return z;
}