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Parse an Integer From Text

MediumStrings243 tests

You get a string text. Read an integer from it, using these steps in order:

  • Skip any space characters (' ') at the start. Only the space character counts here.
  • If the next character is '+' or '-', read it as the sign. Read at most one sign. If there is no sign, the number is positive.
  • Read digits (0 to 9) until you reach a character that is not a digit, or the end of the string. Ignore everything after that.
  • If you read no digits, the result is 0. Leading zeros are allowed ("007" gives 7).
  • Keep the result inside the 32-bit signed range [-2147483648, 2147483647]. If the number is smaller, return -2147483648. If it is bigger, return 2147483647.

Return the integer.

Note

Do not use a built-in function that does all of this for you. A digit string can be much longer than 10 characters, so check the limits as you read each digit.

Examples

Example 1

Input:
" -305xyz"
Output:
-305

Skip the three spaces, read the minus sign, read the digits 305, and stop at the letter x.

Example 2

Input:
"word 42"
Output:
0

The first character is a letter, not a space, sign or digit. No digits are read, so the result is 0.

Example 3

Input:
"9876543210"
Output:
2147483647

The number is bigger than 2147483647, so the result is clamped to 2147483647.

Constraints

  • 0 <= text.length <= 30
  • text contains only English letters, digits, ' ', '+', '-' and '.'.

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