added 109

109. Longest Substring Without Repeating Characters/TEST.cc

@@ -0,0 +1,14 @@
+#define CATCH_CONFIG_MAIN
+#include "../Catch/single_include/catch.hpp"
+#include "solution.h"
+
+TEST_CASE("Longest Substring Without Repeating Characters", "[lengthOfLongestSubstring]")
+{
+    Solution s;
+    REQUIRE( s.lengthOfLongestSubstring("abcabcbb") == 3 );
+    REQUIRE( s.lengthOfLongestSubstring("bbbbb") == 1 );
+    REQUIRE( s.lengthOfLongestSubstring("a") == 1 );
+    REQUIRE( s.lengthOfLongestSubstring("au") == 2 );
+    REQUIRE( s.lengthOfLongestSubstring("bwt") == 3 );
+    REQUIRE( s.lengthOfLongestSubstring("abba") == 2 );
+}

109. Longest Substring Without Repeating Characters/solution.h

@@ -0,0 +1,23 @@
+#include <string>
+using std::string;
+#include <unordered_map>
+using std::unordered_map;
+#include <algorithm>
+using std::max;
+
+class Solution {
+public:
+    int lengthOfLongestSubstring(string s) {
+        size_t ret=0, start=0;
+        unordered_map<char, size_t> cache = {{s.front(), 0}};
+        for (size_t last=1; last < s.size(); ++last) {
+            auto found = cache.find(s[last]);
+            if (found != cache.end() && found->second >= start) {
+                ret = max(ret, last - start);
+                start = found->second + 1;
+            }
+            cache[s[last]] = last;
+        }
+        return max(ret, s.size()-start);
+    }
+};