Question: http://oj.leetcode.com/problems/string-to-integer-atoi/
Question Name: String to Integer (atoi)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | class Solution: # @return an integer def atoi(self, str): INT_MAX, INT_MIN = 2147483647, -2147483648 index = 0 result = 0 sign = 1 # Default we are processing a non-negative number if len(str) == 0: return 0 # The result for empty string is 0. while str[index].isspace(): index += 1 # Discard whitespace if str[index] == "-": sign = -1 if str[index] in "-+": index += 1 # Discard sign char while index < len(str) and str[index].isdigit(): result = result * 10 + (ord(str[index]) - ord("0")) * sign index += 1 # Handle overflow. Because Python could handle the large # integer, this code works well. If with C/C++, we should use # another method. For example, with non-negative number, the # test condition for overflow would be: # if( INT_MAX / 10 < result || INT_MAX - result * 10 < # (ord(str[index]) - ord("0")) ) if sign == 1 and result >= INT_MAX: return INT_MAX elif sign == -1 and result <= INT_MIN: return INT_MIN return result |