Skip to content

Improved description for task 8. #26

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 8 commits into from
Nov 18, 2021
Merged
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
61 changes: 55 additions & 6 deletions src/main/java/g0001_0100/s0008_string_to_integer_atoi/readme.md
Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,7 @@ The algorithm for `myAtoi(string s)` is as follows:
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 `[-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 than `231 - 1` should be clamped to `231 - 1`.
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.

**Note:**
Expand All @@ -24,39 +24,88 @@ The algorithm for `myAtoi(string s)` is as follows:

**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.
**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 \[-2<sup>31</sup>, 2<sup>31</sup> - 1\], 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.
**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 \[-2<sup>31</sup>, 2<sup>31</sup> - 1\], 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.
**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 \[-2<sup>31</sup>, 2<sup>31</sup> - 1\], the final result is 4193.

**Example 4:**

**Input:** s = "words and 987"

**Output:** 0

**Explanation:** Step 1: "words and 987" (no characters read because there is no leading whitespace) ^ Step 2: "words and 987" (no characters read because there is neither a '-' nor '+') ^ 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 \[-231, 231 - 1\], the final result is 0.
**Explanation:**

Step 1: "words and 987" (no characters read because there is no leading whitespace)
^
Step 2: "words and 987" (no characters read because there is neither a '-' nor '+')
^
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 = "-91283472332"

**Output:** -2147483648

**Explanation:** 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 \[-231, 231 - 1\], the final result is clamped to -231 = -2147483648.
**Explanation:**

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:**

Expand Down