Valid Number update

Author: ssfxz

65.cpp

@@ -0,0 +1,104 @@
+class Solution {
+public:
+    bool isNumber(string s) {
+        bool ret = false;
+        int i = 0;
+
+        // space
+        while(s[i] == 32)
+        {
+            ++i;
+        }
+
+        // - or +
+        if(s[i] == 45 || s[i] == 43)
+        {
+            ++i;
+        }
+
+        int len = s.size();
+
+        bool hasDot = false;
+        bool hasE = false;
+        bool hasPart1 = false;
+        bool hasPart2 = false;
+
+        for(; i < len; ++i)
+        {
+            // .
+            if(s[i] == 46 )  
+            {
+                if(hasDot || hasE || (i == 0 && i == len - 1))
+                {   
+                    return false;
+                }
+                else
+                {
+                    hasDot = true;
+                }
+
+            }
+            // e
+            else if(s[i] == 101)
+            {
+                if(hasE || !hasPart1)
+                {   
+                    return false;
+                }
+                else
+                {
+                    hasE = true;
+
+                }
+            }
+            // number
+            else if(s[i] >= 48 && s[i] <= 57)
+            {
+                if (!hasE)
+                {
+                    hasPart1 = true;
+                }
+                else
+                {
+                    hasPart2 = true;
+                }
+            }
+            // - or +
+            else if(s[i] == 45 || s[i] == 43)
+            {
+                if (!hasE || !(s[i-1] == 101))
+                    return false;
+            }
+            // space
+            else if(s[i] == 32)
+            {
+                while(s[i] == 32)
+                {
+                    ++i;
+                }
+                break;
+            }
+            else
+            {
+                return false;
+            }
+        }
+
+        if (!hasPart1)
+        {
+            return false;
+        }
+        else if (hasE && !hasPart2)
+        {
+            return false;
+        }
+        else if (i != len)
+        {
+            return false;
+        }
+        else
+        {
+            return true;
+        }
+    }
+};