# Leetcode 65 Solution

This article provides solution to leetcode question 65 (valid-number)

https://leetcode.com/problems/valid-number

## Solution

``````class Solution {
public:
bool isNumber(string s) {
bool num = false;
bool numAfterExp = true;
bool dot = false;
bool exp = false;
bool sign = false;
int n = s.size();

for (int i = 0; i < n; i++)
{
char ch = s[i];

if (ch == ' ')
{
if (i < n - 1 && s[i + 1] != ' ' && (num || dot || exp || sign))
return false;
}
else if (ch == '+' || ch == '-')
{
if (i > 0 && (s[i - 1] != 'e' && s[i - 1] != ' '))
return false;
sign = true;
}
else if ('0' <= ch && ch <= '9')
{
num = true;
numAfterExp = true;
}
else if (ch == '.')
{
if (exp || dot || (i > 0 && (s[i - 1] != ' ' && s[i - 1] != '+' && s[i - 1] != '-' && !('0' <= s[i - 1] && s[i - 1] <= '9'))))
return false;
dot = true;
}
else if (ch == 'e')
{
if (exp || (i == 0 || (!('0' <= s[i - 1] && s[i - 1] <= '9') && s[i - 1] != '.') || num == false))
return false;
exp = true;
numAfterExp = false;
}
else
return false;
}

return num && numAfterExp;
}
};
``````