Restored task 8

Author: javadev

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

@@ -2,87 +2,115 @@
 
 Medium
 
-Implement the `myAtoi(string s)` function, which converts a string to a 32-bit signed integer.
+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:
 
-1.  **Whitespace**: Ignore any leading whitespace (`" "`).
-2.  **Signedness**: Determine the sign by checking if the next character is `'-'` or `'+'`, assuming positivity if neither present.
-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.
-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>.
+1.  Read in and ignore any leading whitespace.
+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.
+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.
+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).
+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>.
+6.  Return the integer as the final result.
 
-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:**
+**Explanation:** The underlined characters are what is read in, the caret is the current reader position.
 
-    The underlined characters are what is read in and 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 [-2<sup>31</sup>, 2<sup>31</sup> - 1], the final result is 42. 
 
 **Example 2:**
 
-**Input:** s = " -042"
+**Input:** s = " -42"
 
-**Output:** \-42
+**Output:** -42
 
 **Explanation:**
 
-    Step 1: "___-042" (leading whitespace is read and ignored)
-                ^
-    Step 2: " -042" ('-' is read, so the result should be negative)
-              ^
-    Step 3: " -042" ("042" is read in, leading zeros ignored in the result)
-                 ^ 
+    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 [-2<sup>31</sup>, 2<sup>31</sup> - 1], the final result is -42. 
 
 **Example 3:**
 
-**Input:** s = "1337c0d3"
+**Input:** s = "4193 with words"
 
-**Output:** 1337
+**Output:** 4193
 
 **Explanation:**
 
-    Step 1: "1337c0d3" (no characters read because there is no leading whitespace)
+    Step 1: "4193 with words" (no characters read because there is no leading whitespace)
              ^
-    Step 2: "1337c0d3" (no characters read because there is neither a '-' nor '+')
+    Step 2: "4193 with words" (no characters read because there is neither a '-' nor '+')
              ^
-    Step 3: "1337c0d3" ("1337" is read in; reading stops because the next character is a non-digit)
+    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 [-2<sup>31</sup>, 2<sup>31</sup> - 1], the final result is 4193. 
 
 **Example 4:**
 
-**Input:** s = "0-1"
+**Input:** s = "words and 987"
 
 **Output:** 0
 
 **Explanation:**
 
-    Step 1: "0-1" (no characters read because there is no leading whitespace)
+    Step 1: "words and 987" (no characters read because there is no leading whitespace)
              ^
-    Step 2: "0-1" (no characters read because there is neither a '-' nor '+')
+    Step 2: "words and 987" (no characters read because there is neither a '-' nor '+')
              ^
-    Step 3: "0-1" ("0" is read in; reading stops because the next character is a non-digit)
-              ^ 
+    Step 3: "words and 987" (reading stops immediately because there is a non-digit 'w')
+             ^
+    The parsed integer is 0 because no digits were read.
+
+Since 0 is in the range [-2<sup>31</sup>, 2<sup>31</sup> - 1], the final result is 0. 
 
 **Example 5:**
 
-**Input:** s = "words and 987"
+**Input:** s = "-91283472332"
 
-**Output:** 0
+**Output:** -2147483648
 
 **Explanation:**
 
-Reading stops at the first non-digit character 'w'.
+    Step 1: "-91283472332" (no characters read because there is no leading whitespace)
+            ^
+    Step 2: "-91283472332" ('-' is read, so the result should be negative)
+              ^
+    Step 3: "-91283472332" ("91283472332" is read in)
+                         ^
+    The parsed integer is -91283472332.
+
+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.  
+
+**Constraints:**
+
+*   `0 <= s.length <= 200`
+*   `s` consists of English letters (lower-case and upper-case), digits (`0-9`), `' '`, `'+'`, `'-'`, and `'.'`.
 
 To solve the String to Integer (atoi) problem in Java using a `Solution` class, we'll follow these steps:
 
@@ -153,9 +181,4 @@ public class Solution {
 }
 ```
 
-This implementation provides a solution to the String to Integer (atoi) problem in Java.
-
-**Constraints:**
-
-*   `0 <= s.length <= 200`
-*   `s` consists of English letters (lower-case and upper-case), digits (`0-9`), `' '`, `'+'`, `'-'`, and `'.'`.
+This implementation provides a solution to the String to Integer (atoi) problem in Java.