chore(Java): added boyer moore search (#511)

algorithms/Java/README.md

@@ -75,6 +75,7 @@
 5. [Split String](strings/SplitString.java)
 6. [Tokenizer](strings/tokenizer.java)
 7. [Anagram](strings/anagram.java)
+8. [Boyer Moore Search](strings/Boyer_Moore.java)
 
 ## Trees
 

algorithms/Java/strings/Boyer_Moore.java

@@ -0,0 +1,88 @@
+/* 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);
+	}
+}