无重复字符的最长子串

Author: haotf

Diff for: 3.无重复字符的最长子串.java

@@ -0,0 +1,37 @@
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+/*
+ * @lc app=leetcode.cn id=3 lang=java
+ *
+ * [3] 无重复字符的最长子串
+ */
+
+// @lc code=start
+class Solution {
+    public int lengthOfLongestSubstring(String s) {
+
+        Map<Character, Integer> map = new HashMap<Character, Integer>();
+
+        int max = 0;
+        int left = 0;
+        int right = 0;
+
+        while (right < s.length()) {
+            char r = s.charAt(right);
+            map.put(r, map.getOrDefault(r, 0) + 1);
+            right++;
+            while (map.get(r) > 1) {
+                char l = s.charAt(left);
+                map.put(l, map.get(l) - 1);
+                left++;
+            }
+            max = Math.max(max, right - left);
+        }
+
+        return max;
+    }
+}
+// @lc code=end