/* Java Program for Bad Character Heuristic of Boyer
Moore String Matching Algorithm */


class AWQ{
	
	static int NO_OF_CHARS = 256;
	
	//A utility function to get maximum of two integers
	static int max (int a, int b) { return (a > b)? a: b; }

	//The preprocessing function for Boyer Moore's
	//bad character heuristic
	static void badCharHeuristic( char []str, int size,int badchar[])
	{

	// Initialize all occurrences as -1
	for (int i = 0; i < NO_OF_CHARS; i++)
		badchar[i] = -1;

	for (int i = 0; i < size; i++)
		badchar[(int) str[i]] = i;
	}

	/* A pattern searching function that uses Bad
	Character Heuristic of Boyer Moore Algorithm */
	static void search( char txt[], char pat[])
	{
	int m = pat.length;
	int n = txt.length;

	int badchar[] = new int[NO_OF_CHARS];

	/* Fill the bad character array by calling
		the preprocessing function badCharHeuristic()
		for given pattern */
	badCharHeuristic(pat, m, badchar);

	int s = 0;
	while(s <= (n - m))
	{
		int j = m-1;

		/* Keep reducing index j of pattern while
			characters of pattern and text are
			matching at this shift s */
		while(j >= 0 && pat[j] == txt[s+j])
			j--;

		/* If the pattern is present at current
			shift, then index j will become -1 after
			the above loop */
		if (j < 0)
		{
			System.out.println("Patterns occur at shift = " + s);

			/* Shift the pattern so that the next
				character in text aligns with the last
				occurrence of it in pattern.
				The condition s+m < n is necessary for
				the case when pattern occurs at the end
				of text */
			//txt[s+m] is character after the pattern in text
			s += (s+m < n)? m-badchar[txt[s+m]] : 1;

		}

		else
			/* Shift the pattern so that the bad character
				in text aligns with the last occurrence of
				it in pattern. The max function is used to
				make sure that we get a positive shift.
				We may get a negative shift if the last
				occurrence of bad character in pattern
				is on the right side of the current
				character. */
			s += max(1, j - badchar[txt[s+j]]);
	}
	}

	/* Driver program to test above function */
	public static void main(String []args) {
		
		char txt[] = "ABAAABCD".toCharArray();
		char pat[] = "ABC".toCharArray();
		search(txt, pat);
	}
}