Add phase1, phase2, phase3 code

Author: colorbox

125/1.cpp

@@ -0,0 +1,20 @@
+class Solution {
+public:
+    bool isPalindrome(string s) {
+        string checker = s;
+        checker.erase(
+            remove_if(checker.begin(), checker.end(), [](unsigned char c) { return !isalnum(c); } ),
+            checker.end()
+        );
+
+        for (int i=0; i < checker.size(); i++) {
+            checker[i] = tolower(checker[i]);
+        }
+
+        string checkerReverse = checker;
+
+        reverse(checkerReverse.begin(), checkerReverse.end());
+
+        return (checker == checkerReverse);
+    }
+};

125/2.cpp

@@ -0,0 +1,18 @@
+class Solution {
+public:
+    bool isPalindrome(string s) {
+        string checker;
+
+        for (char c: s) {
+            if (isalnum(c)) {
+                checker += tolower(c);
+            }
+        }
+
+        string checkerReverse = checker;
+
+        reverse(checkerReverse.begin(), checkerReverse.end());
+
+        return (checker == checkerReverse);
+    }
+};

125/3.cpp

@@ -0,0 +1,18 @@
+class Solution {
+public:
+    bool isPalindrome(string s) {
+        if (s.empty()) abort();
+
+        string checker;
+        for (char c: s) {
+            if (isalnum(c)) {
+                checker += tolower(c);
+            }
+        }
+
+        string reversedChecker = checker;
+        reverse(reversedChecker.begin(), reversedChecker.end());
+
+        return reversedChecker == checker;
+    }
+};