problem 3

LengthOfLongestSubstring.cs

@@ -0,0 +1,30 @@
+public class Solution {
+    public int LengthOfLongestSubstring(string s) {
+        int max = 0;
+        int n = 0;
+        for (int i = 0; i < s.Length; i++)
+        {
+            n++;
+            if (n > 1)
+            {
+                n -= FindDuplicateCharacter(s.Substring(i - n + 1, n)) + 1;
+            }
+            if (n > max) {
+                max = n;
+            }
+        }
+        return max;
+    }
+
+    public int FindDuplicateCharacter(string s) {
+        char last = s[s.Length - 1];
+        for (int i = 0; i < s.Length - 1; i++)
+        {
+            if (s[i] == last)
+            {
+                return i;
+            }
+        }
+        return -1;
+    }
+}