feat: solved 3

Author: fghpdf

src/com/fghpdf/LongestSubstringWithoutRepeatingCharacters/Solution.java

@@ -0,0 +1,41 @@
+package com.fghpdf.LongestSubstringWithoutRepeatingCharacters;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * @author fghpdf
+ * @date 2019/11/9
+ *
+ * https://leetcode.com/problems/longest-substring-without-repeating-characters/
+ * two pointer and a map to save the char position
+ * first pointer is to loop string
+ * second pointer is to jump to the repeat position
+ * when I found repeat char, the substring is over
+ * so I should start from the last char of the substring
+ **/
+public class Solution {
+	public int lengthOfLongestSubstring(String s) {
+		if (s == null || "".equals(s)) {
+			return 0;
+		}
+		Map<Character, Integer> position = new HashMap<>(26);
+
+		int maxLength = -1;
+		for (int i = 0, repeatPosition = 0; i < s.length(); i++) {
+			char c = s.charAt(i);
+			if (position.get(c) != null) {
+				repeatPosition = Math.max(repeatPosition, position.get(c) + 1);
+				System.out.println(repeatPosition);
+			}
+			position.put(c, i);
+			maxLength = Math.max(i - repeatPosition + 1, maxLength);
+		}
+		return maxLength;
+	}
+
+	public static void main(String[] args) {
+		Solution sol = new Solution();
+		System.out.println(sol.lengthOfLongestSubstring("abcabcdd"));
+	}
+}