Improved task 65.

Author: javadev

src/main/java/g0001_0100/s0065_valid_number/Solution.java

@@ -2,49 +2,41 @@
 
 public class Solution {
     public boolean isNumber(String s) {
-        // Variables
-        boolean seenDigit = false;
-        boolean seenExponent = false;
-        boolean seenDot = false;
+
+        if (s == null || s.length() == 0) {
+            return false;
+        }
+
+        boolean eSeen = false;
+        boolean numberSeen = false;
+        boolean decimalSeen = false;
+
         for (int i = 0; i < s.length(); i++) {
-            char ch = s.charAt(i);
-            if (Character.isDigit(ch)) {
-                seenDigit = true;
-            } else {
-                // Check Exponent logic
-                if (ch == 'e' || ch == 'E') {
-                    // Should have seen at least one digit before
-                    // Shouldn't see exponent > 1 time
-                    if (seenDigit && !seenExponent) {
-                        seenExponent = true;
-                        // Reset seenDigit because at least one digit should come after seeing
-                        // exponent
-                        // Return statement is returning seenDigit flag
-                        seenDigit = false;
-                    } else {
-                        return false;
-                    }
-                } else if (ch == '.') {
-                    // Validate there is only one dot
-                    // Shouldn't have seen dot before as there can be only one
-                    // Shouldn't have see exponent before
-                    if (seenDot || seenExponent) {
-                        return false;
-                    } else {
-                        seenDot = true;
-                    }
-                } else if (ch == '+' || ch == '-') {
-                    // Validate sign coming at 0th position or after e/E
-                    // Sign can only come at starting or after e
-                    // That's the reason sign check do at the end
-                    if (!(i == 0 || s.charAt(i - 1) == 'e' || s.charAt(i - 1) == 'E')) {
-                        return false;
-                    }
-                } else {
+            char c = s.charAt(i);
+            if (c >= 48 && c <= 57) {
+                numberSeen = true;
+            } else if (c == '+' || c == '-') {
+                if (i == s.length() - 1
+                        || (i != 0 && s.charAt(i - 1) != 'e' && s.charAt(i - 1) != 'E')) {
+                    return false;
+                }
+            } else if (c == '.') {
+                if (eSeen || decimalSeen) {
                     return false;
                 }
+
+                decimalSeen = true;
+            } else if (c == 'e' || c == 'E') {
+                if (i == s.length() - 1 || eSeen || !numberSeen) {
+                    return false;
+                }
+
+                eSeen = true;
+            } else {
+                return false;
             }
         }
-        return seenDigit;
+
+        return numberSeen;
     }
 }

src/test/java/g0001_0100/s0065_valid_number/SolutionTest.java

@@ -7,7 +7,11 @@
 
 public class SolutionTest {
     @Test
-    public void validNumber() {
-        assertThat(new Solution().isNumber("0"), equalTo(true));
+    public void isNumber() {
+        Solution solution = new Solution();
+        assertThat(solution.isNumber("0"), equalTo(true));
+        assertThat(solution.isNumber("e"), equalTo(false));
+        assertThat(solution.isNumber("."), equalTo(false));
+        assertThat(solution.isNumber(".1"), equalTo(true));
     }
 }