Add 340_Longest_Substring_with_At_Most_K_Distinct_Characters.java

Author: Sean Prashad

Sliding Window/340_Longest_Substring_with_At_Most_K_Distinct_Characters.java

@@ -0,0 +1,27 @@
+class Solution {
+    public int lengthOfLongestSubstringKDistinct(String s, int k) {
+        if (s == null || s.length() == 0) {
+            return 0;
+        }
+
+        int result = 0, distinctNums = 0;
+        int[] map = new int[256];
+
+        for (int i = 0, j = 0; j < s.length(); j++) {
+            if (map[s.charAt(j)]++ == 0) {
+                distinctNums++;
+            }
+
+            while (distinctNums > k) {
+                if (--map[s.charAt(i)] == 0) {
+                    distinctNums--;
+                }
+                ++i;
+            }
+
+            result = Math.max(result, j - i + 1);
+        }
+
+        return result;
+    }
+}