// CSE 143, Autumn 2013
// This program uses recursive backtracking to print all permutations
// of a given string.

public class Permutations {
	public static void main(String[] args) {
		permute("TEAM");
	}
	
	// Outputs all permutations of the given string, one per line.
	// For example, TEAM can be permuted into MEAT, META, TMEA, ...
    public static void permute(String s) {                                   
    	permute(s, "");
    }
    
    // Private recursive helper to implement permute logic.
    // Adds a 'chosen' parameter representing all characters that
    // have been chosen so far.
    private static void permute(String s, String chosen) {
    	if(s.length() == 0) {
    		// Base case; all characters have been chosen.  Print!
    		System.out.println(chosen);
    	} else {
    		// Recursive case; s contains some characters to permute.
    		// for each possible choice,
    		for(int i = 0; i < s.length(); i++) {
    			// choose a character from s (and remove it)
    			char c = s.charAt(i);
    			String rest = s.substring(0, i) + s.substring(i + 1);
    			
    			// explore
    			permute(rest, chosen + c);
    			
    			// unchoose (nothing to do because we didn't modify s)
    		}
    	}
    }
}