Create 65. Valid Number

Author: rajatag03

Diff for: 65. Valid Number

@@ -0,0 +1,66 @@
+class Solution {
+    public boolean isNumber(String s) {
+        boolean digitseen =false, eseen = false, dotseen=false;
+        int countPlusMinus = 0;
+        
+        for(int i=0;i<s.length();i++){
+            char ch = s.charAt(i);
+            
+            //digit
+            if(Character.isDigit(ch)){
+                digitseen = true;
+            }
+            //minus/plus
+            else if(ch =='+' || ch == '-'){
+                if(countPlusMinus == 2){
+                    return false;
+                }
+                
+                if(i>0 && (s.charAt(i-1) != 'e' && s.charAt(i-1) != 'E')){
+                    return false;
+                }
+                
+                if(i == s.length()-1){
+                    return false;
+                }
+                
+                countPlusMinus++;
+            }
+            //dot
+            else if(ch == '.'){
+                if(eseen || dotseen){
+                    return false;
+                }
+                
+                if(i == s.length() -1 && !digitseen){
+                    return false;
+                }
+                
+                dotseen = true;
+            }
+            
+            //e/E
+            else if(ch == 'e' || ch == 'E'){
+                if(eseen || !digitseen || i == s.length()-1){
+                    return false;
+                }
+                
+                eseen = true;
+            }
+            else{
+                return false;
+            }
+            
+        }
+        
+        return true;
+    }
+}
+	
+import java.util.regex.*;
+class Solution {
+    public boolean isNumber(String s) {
+        return Pattern.matches("^([+-]?(((\\d+\\.\\d*)|(\\.\\d+))|(\\d+))([eE][+-]?\\d+)?)$", s);
+    }
+    
+}