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  • src/main/java/g0001_0100/s0008_string_to_integer_atoi

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‎src/main/java/g0001_0100/s0008_string_to_integer_atoi/readme.md‎

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Implement the`myAtoi(string s)` function, which converts a string to a 32-bit signed integer.
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Implement the`myAtoi(string s)` function, which converts a string to a 32-bit signed integer (similar to C/C++'s`atoi` function).
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The algorithm for`myAtoi(string s)` is as follows:
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1.**Whitespace**: Ignore any leading whitespace (`" "`).
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2.**Signedness**: Determine the sign by checking if the next character is`'-'` or`'+'`, assuming positivity if neither present.
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3.**Conversion**: Read the integer by skipping leading zeros until a non-digit character is encountered or the end of the string is reached. If no digits were read, then the result is 0.
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4.**Rounding**: If the integer is out of the 32-bit signed integer range <code>[-2<sup>31</sup>, 2<sup>31</sup> - 1]</code>, then round the integer to remain in the range. Specifically, integers less than <code>-2<sup>31</sup></code> should be rounded to <code>-2<sup>31</sup></code>, and integers greater than <code>2<sup>31</sup> - 1</code> should be rounded to <code>2<sup>31</sup> - 1</code>.
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1. Read in and ignore any leading whitespace.
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2. 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.
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3. 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.
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4. Convert these digits into an integer (i.e.`"123" -> 123`,`"0032" -> 32`). If no digits were read, then the integer is`0`. Change the sign as necessary (from step 2).
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5. If the integer is out of the 32-bit signed integer range <code>[-2<sup>31</sup>, 2<sup>31</sup> - 1]</code>, then clamp the integer so that it remains in the range. Specifically, integers less than <code>-2<sup>31</sup></code> should be clamped to <code>-2<sup>31</sup></code>, and integers greater than <code>2<sup>31</sup> - 1</code> should be clamped to <code>2<sup>31</sup> - 1</code>.
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6. Return the integer as the final result.
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Return the integer as the final result.
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**Note:**
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* Only the space character`' '` is considered a whitespace character.
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***Do not ignore** any characters other than the leading whitespace or the rest of the string after the digits.
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**Example 1:**
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**Input:** s = "42"
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**Output:** 42
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**Explanation:**
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**Explanation:** The underlined characters are what is read in, the caret is the current reader position.
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The underlined characters are what is read in and the caret is the current reader position.
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Step 1: "42" (no characters read because there is no leading whitespace)
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^
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^
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Step 2: "42" (no characters read because there is neither a '-' nor '+')
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^
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Step 3: "42" ("42" is read in)
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^
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^
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The parsed integer is 42. Since 42 is in the range[-2<sup>31</sup>, 2<sup>31</sup> - 1], the final result is 42.
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**Example 2:**
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**Input:** s = " -042"
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**Input:** s = " -42"
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**Output:**\-42
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**Output:** -42
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**Explanation:**
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Step 1: "___-042" (leading whitespace is read and ignored)
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^
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Step 2: " -042" ('-' is read, so the result should be negative)
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^
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Step 3: " -042" ("042" is read in, leading zeros ignored in the result)
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^
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Step 1: " -42" (leading whitespace is read and ignored)
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^
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Step 2: " -42" ('-' is read, so the result should be negative)
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^
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Step 3: " -42" ("42" is read in)
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^
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The parsed integer is -42.
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Since -42 is in the range[-2<sup>31</sup>, 2<sup>31</sup> - 1], the final result is -42.
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**Example 3:**
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**Input:** s = "1337c0d3"
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**Input:** s = "4193 with words"
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**Output:**1337
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**Output:**4193
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**Explanation:**
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Step 1: "1337c0d3" (no characters read because there is no leading whitespace)
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Step 1: "4193 with words" (no characters read because there is no leading whitespace)
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^
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Step 2: "1337c0d3" (no characters read because there is neither a '-' nor '+')
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Step 2: "4193 with words" (no characters read because there is neither a '-' nor '+')
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^
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Step 3: "1337c0d3" ("1337" is read in; reading stops because the next character is a non-digit)
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Step 3: "4193 with words" ("4193" is read in; reading stops because the next character is a non-digit)
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^
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The parsed integer is 4193.
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Since 4193 is in the range[-2<sup>31</sup>, 2<sup>31</sup> - 1], the final result is 4193.
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**Example 4:**
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**Input:** s = "0-1"
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**Input:** s = "words and 987"
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**Output:** 0
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**Explanation:**
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Step 1: "0-1" (no characters read because there is no leading whitespace)
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Step 1: "words and 987" (no characters read because there is no leading whitespace)
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^
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Step 2: "0-1" (no characters read because there is neither a '-' nor '+')
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Step 2: "words and 987" (no characters read because there is neither a '-' nor '+')
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^
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Step 3: "0-1" ("0" is read in; reading stops because the next character is a non-digit)
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^
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Step 3: "words and 987" (reading stops immediately because there is a non-digit 'w')
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^
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The parsed integer is 0 because no digits were read.
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Since 0 is in the range[-2<sup>31</sup>, 2<sup>31</sup> - 1], the final result is 0.
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**Example 5:**
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**Input:** s = "words and 987"
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**Input:** s = "-91283472332"
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**Output:**0
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**Output:**-2147483648
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**Explanation:**
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Reading stops at the first non-digit character 'w'.
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Step 1: "-91283472332" (no characters read because there is no leading whitespace)
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^
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Step 2: "-91283472332" ('-' is read, so the result should be negative)
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^
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Step 3: "-91283472332" ("91283472332" is read in)
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^
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The parsed integer is -91283472332.
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Since -91283472332 is less than the lower bound of the range[-2<sup>31</sup>, 2<sup>31</sup> - 1], the final result is clamped to -2<sup>31</sup> = -2147483648.
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**Constraints:**
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*`0 <= s.length <= 200`
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*`s` consists of English letters (lower-case and upper-case), digits (`0-9`),`' '`,`'+'`,`'-'`, and`'.'`.
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To solve the String to Integer (atoi) problem in Java using a`Solution` class, we'll follow these steps:
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}
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```
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This implementation provides a solution to the String to Integer (atoi) problem in Java.
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**Constraints:**
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*`0 <= s.length <= 200`
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*`s` consists of English letters (lower-case and upper-case), digits (`0-9`),`' '`,`'+'`,`'-'`, and`'.'`.
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This implementation provides a solution to the String to Integer (atoi) problem in Java.

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