Levenshtein java

lev.java

public static char NULL = '\u0000';    

public static int cout(char x, char y){
	if(x == NULL){ //insertion
		return 1;
	}
	if(y == NULL){ //insertion
		return 1;
	}
	if(x != y){ //substitution
		return 1;
	}
	return 0;
}

public static int distance(String a, String b){
	int[][] dist = new int[a.length()+1][b.length()+1];
	char X,Y;
	int d1,d2,d3;
	
	for(int i = 1;i <= a.length();i++){
		X = a.charAt(i-1);
		dist[i][0] = dist[i-1][0] + cout(X,NULL);
	}
	for(int j = 1;j <= b.length();j++){
		Y = b.charAt(j-1);
		dist[0][j] = dist[0][j] + cout(NULL,Y);
	}
	for(int i = 1;i <= a.length();i++){
		X = a.charAt(i-1);
    	for(int j = 1;j <= b.length();j++){
    		Y = b.charAt(j-1);
    		d1 = dist[i-1][j-1] + cout(X,Y);
    		d2 = dist[i-1][j] + cout(X,NULL);
    		d3 = dist[i][j-1] + cout(NULL,Y);
    		
    		dist[i][j] = Math.min(d1, Math.min(d2,d3));
    	}
	}
	return dist[a.length()][b.length()];
}