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Author: assassint2017

First Unique Character in a String/First_Unique_Character_in_a_String.cpp

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+// Runtime: 48 ms, faster than 62.52% of C++ online submissions for First Unique Character in a String.
+// Memory Usage: 12.8 MB, less than 90.63% of C++ online submissions for First Unique Character in a String.
+
+class Solution 
+{
+public:
+    int firstUniqChar(string s) 
+    {
+        vector<bool> repeat(26, false);
+        vector<int> memo(26, -1);
+        
+        for (int i = 0; i < s.length(); ++i)
+        {
+            if (memo[s[i] - 'a'] != -1)
+            {
+                repeat[s[i] - 'a'] = true;
+            }
+            
+            memo[s[i] - 'a'] = i;
+        }
+        
+        int res = -1;
+        for (int i = 0; i < 26; ++i)
+        {
+            if (repeat[i] == false && memo[i] != -1)
+            {
+                if (res < 0)
+                {
+                    res = memo[i];
+                }
+                else
+                {
+                    res = min(res, memo[i]);
+                }
+            }
+        }
+        
+        return res;
+    }
+};