add 125 solution[js]

Author: limbowandering

solution/125.Valid Palindrome/Solution.js

@@ -0,0 +1,48 @@
+const isPalindrome1 = function(s){
+  let arr1 = [], arr2 = [];
+  for(let i = 0; i < s.length; i++){
+    if(s[i] >= 'A' && s[i] <= 'Z' ){
+      arr1.push(s[i].toLowerCase());
+    }
+    if(s[i] >= '0' && s[i] <= '9'||
+    s[i] >= 'a' && s[i] <= 'z'){
+      arr1.push(s[i]);
+    }
+  }
+  arr2 = [...arr1];
+  arr2.reverse();
+  return arr1.join('') === arr2.join('');
+}
+
+const isPalindrome = function(s){
+  function isNumOrAl(a){
+    if(a >= 'A' && a <= 'Z' ||
+    a >= '0' && a <= '9'||
+    a >= 'a' && a <= 'z'){
+      return true;
+    }
+    else{
+      return false;
+    }
+  }
+
+  if(s.length === 0){
+    return true;
+  }
+  let i = 0, j = s.length - 1;
+  while(i < j){
+    while(i < j && !isNumOrAl(s[i])){
+      i++;
+    }
+    while(i < j && !isNumOrAl(s[j])){
+      j--;
+    }
+    if(s[i].toLowerCase() !== s[j].toLowerCase()){
+      return false;
+    }else{
+      i++;
+      j--;
+    }
+  }
+  return true;
+};