leetcode:Q28实现strStr

1.按位匹配，每次发现首字母匹配则记录当前的位置，继续向后匹配。
2.如果匹配过程中发现不匹配了，则回到首字母匹配的位置+1 继续匹配。

#3

data-structure-and-algorithms/src/main/java/com/github/liaojiacan/lintcode/Q28实现strStr/Solution.java

@@ -0,0 +1,47 @@
+package com.github.liaojiacan.lintcode.Q28实现strStr;
+
+/**
+ * @author liaojiacan
+ * @date 2019/1/30
+ */
+class Solution {
+	public int strStr(String haystack, String needle) {
+
+		if("".equals(needle)){
+			return 0;
+		}
+
+		if(needle.length()>haystack.length()){
+			return -1;
+		}
+		char[] haystackChars = haystack.toCharArray();
+		char[] needleChars = needle.toCharArray();
+		int index = -1;
+		int p = 0;
+		for(int i=0;i<haystackChars.length;++i){
+
+			if(p < needleChars.length && haystackChars[i] == needleChars[p]){
+				p++;
+				if(index == -1){
+					index = i;
+				}
+				if(p==needleChars.length){
+					return index;
+				}
+			}else{
+				p=0;
+				if(index != -1){
+					i = index;
+				}
+				index = -1;
+			}
+
+		}
+
+		return -1;
+	}
+
+	public static void main(String[] args) {
+		System.out.println(new Solution().strStr("mississippi","pi"));
+	}
+}