Here, We see String to Integer LeetCode Solution. This Leetcode problem is done in many programming languages like C++, Java, JavaScript, Python, etc. with different approaches.
List of all LeetCode Solution
String to Integer LeetCode Solution
Table of Contents
Problem Statement
Implement the myAtoi(string s)
function, which converts a string to a 32-bit signed integer (similar to C/C++’s atoi
function).
The algorithm for myAtoi(string s)
is as follows:
- Read in and ignore any leading whitespace.
- Check if the next character (if not already at the end of the string) is
'-'
or'+'
. Read this character in if it is either. This determines if the final result is negative or positive respectively. Assume the result is positive if neither is present. - Read in next the characters until the next non-digit character or the end of the input is reached. The rest of the string is ignored.
- Convert these digits into an integer (i.e.
"123" -> 123
,"0032" -> 32
). If no digits were read, then the integer is0
. Change the sign as necessary (from step 2). - If the integer is out of the 32-bit signed integer range
[-231, 231 - 1]
, then clamp the integer so that it remains in the range. Specifically, integers less than-231
should be clamped to-231
, and integers greater than231 - 1
should be clamped to231 - 1
. - Return the integer as the final result.
Note:
- Only the space character
' '
is considered a whitespace character. - Do not ignore any characters other than the leading whitespace or the rest of the string after the digits.
Example 1:
Input: s = “42”
Output: 42
Explanation: The underlined characters are what is read in, the caret is the current reader position.
Step 1: “42” (no characters read because there is no leading whitespace) ^
Step 2: “42” (no characters read because there is neither a ‘-‘ nor ‘+’) ^
Step 3: “42” (“42” is read in) ^ The parsed integer is 42. Since 42 is in the range [-231, 231 – 1], the final result is 42.
Example 2:
Input: s = ” -42″
Output: -42
Explanation:
Step 1: ” -42″ (leading whitespace is read and ignored) ^
Step 2: ” -42″ (‘-‘ is read, so the result should be negative) ^
Step 3: ” -42″ (“42” is read in) ^ The parsed integer is -42. Since -42 is in the range [-231, 231 – 1], the final result is -42.
Example 3:
Input: s = “4193 with words”
Output: 4193
Explanation:
Step 1: “4193 with words” (no characters read because there is no leading whitespace) ^
Step 2: “4193 with words” (no characters read because there is neither a ‘-‘ nor ‘+’) ^
Step 3: “4193 with words” (“4193” is read in; reading stops because the next character is a non-digit) ^ The parsed integer is 4193. Since 4193 is in the range [-231, 231 – 1], the final result is 4193.
String to Integer LeetCode Solution C++
class Solution {
public:
int myAtoi(string s) {
int len = s.size();
double num = 0;
int i=0;
while(s[i] == ' '){
i++;
}
bool positive = s[i] == '+';
bool negative = s[i] == '-';
positive == true ? i++ : i;
negative == true ? i++ : i;
while(i < len && s[i] >= '0' && s[i] <= '9'){
num = num*10 + (s[i]-'0');
i++;
}
num = negative ? -num : num;
cout<<num<<endl;
num = (num > INT_MAX) ? INT_MAX : num;
num = (num < INT_MIN) ? INT_MIN : num;
cout<<num<<endl;
return int(num);
}
};
Code language: PHP (php)
String to Integer LeetCode Solution Java
class Solution {
public int myAtoi(String s) {
if (s.equals("")) {
return 0;
}
int res = 0, i = 0, sign = 1;
while (i < s.length() && s.charAt(i) == ' ') {
i++;
}
if (i < s.length() && (s.charAt(i) == '+' || s.charAt(i) == '-')) {
if (s.charAt(i++) == '-') {
sign = -1;
}
}
while (i < s.length() && s.charAt(i) >= '0' && s.charAt(i) <= '9') {
if (res > Integer.MAX_VALUE / 10 || (res == Integer.MAX_VALUE / 10 && s.charAt(i) - '0' > 7)) {
if (sign == -1) {
return Integer.MIN_VALUE;
}
return Integer.MAX_VALUE;
}
res = res * 10 + (s.charAt(i++) - '0');
}
return sign * res;
}
}
Code language: JavaScript (javascript)
String to Integer LeetCode Solution JavaScript
var myAtoi = function(s) {
s = s.trim();
if (s.length === 0) {
return 0;
}
let num = 0;
let i = 0;
let sign = 1;
if (s[i] === '+') {
i++;
} else if (s[i] === '-') {
i++;
sign = -1;
}
while (i < s.length && /^\d$/.test(s[i])) {
num = num * 10 + parseInt(s[i]);
i++;
}
num *= sign;
num = Math.max(Math.min(num, Math.pow(2, 31) - 1), -Math.pow(2, 31));
return num;
}
Code language: JavaScript (javascript)
String to Integer LeetCode Solution Python
class Solution(object):
def myAtoi(self, s):
s = s.strip()
if not s:
return 0
num = 0
i = 0
sign = 1
if s[i] == '+':
i += 1
elif s[i] == '-':
i += 1
sign = -1
while i < len(s) and s[i].isdigit():
num = num * 10 + int(s[i])
i += 1
num *= sign
num = max(min(num, 2 ** 31 - 1), -2 ** 31)
return num
Code language: HTML, XML (xml)