USACO OPEN11 Problem 'stringe' Analysis

by Lewin Gan

There is one method that will be very useful, which is the substring method. If S is the string, then it is called, in C/C++ "S.substr(a,b)", in Java, "S.substring(a,b)", and in Pascal "SubStr(S,a,b)", where a represents the starting point, and b represents the ending point (except in pascal, where it represents the number of characters). The parameter b is actually optional, since if we leave it out, it will just take all the characters to the end. Using this method, and string concatenation, one iteration of the function will look like:

S = S.substr(n)+S;

where n is given in the original problem statement. It's now a simple manner of iterating this function until we get our desired answer.

A C++ implementation by Fatih is shown below:

#include <fstream>
using namespace std;

int main()
{
	ifstream fin("stringe.in");
	ofstream fout("stringe.out");
	int z,n,c;
	string s;
	fin >> z;
	for (int i=0; i<z; i++)
	{
		fin >> n >> c >> s;
		for (int j=0; j<c; j++)
			s=s.substr(n)+s;
		fout << s << endl;
	}

	fin.close();
	fout.close();
}