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| 1 | +packageeasy; |
| 2 | +/**8. String to Integer (atoi) QuestionEditorial Solution My Submissions |
| 3 | +Total Accepted: 115114 |
| 4 | +Total Submissions: 839893 |
| 5 | +Difficulty: Easy |
| 6 | +Implement atoi to convert a string to an integer. |
| 7 | +
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| 8 | +Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possible input cases. |
| 9 | +
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| 10 | +Notes: It is intended for this problem to be specified vaguely (ie, no given input specs). You are responsible to gather all the input requirements up front.*/ |
| 11 | + |
| 12 | +/**Requirements for atoi: |
| 13 | +The function first discards as many whitespace characters as necessary until the first non-whitespace character is found. Then, starting from this character, takes an optional initial plus or minus sign followed by as many numerical digits as possible, and interprets them as a numerical value. |
| 14 | +
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| 15 | +The string can contain additional characters after those that form the integral number, which are ignored and have no effect on the behavior of this function. |
| 16 | +
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| 17 | +If the first sequence of non-whitespace characters in str is not a valid integral number, or if no such sequence exists because either str is empty or it contains only whitespace characters, no conversion is performed. |
| 18 | +
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| 19 | +If no valid conversion could be performed, a zero value is returned. If the correct value is out of the range of representable values, INT_MAX (2147483647) or INT_MIN (-2147483648) is returned.*/ |
| 20 | +publicclassStringToInteger { |
| 21 | +publicintmyAtoi(Stringstr) { |
| 22 | +//case 1: str is greater than Integer.MAX_VALUE, return Integer.MAX_VALUE as the question states it |
| 23 | + |
| 24 | +//case 2: str is smaller than Integer.MIN_VALUE, return Integer.MIN_VALUE as the question states it |
| 25 | + |
| 26 | +//case 3: str contains non-numeric values |
| 27 | + |
| 28 | +//case 4: there're many leading whitespace characters which we'll have to ignore |
| 29 | + |
| 30 | +//case 5: when finding the first non-whitespace character, it could possibly be a '+' or '-' sign, after that, we parse all the consecutive numbers |
| 31 | +return0; |
| 32 | +} |
| 33 | +} |