1.trim
2.符号
3.overflow
1 public class Solution { 2 public int atoi(String str) { 3 // IMPORTANT: Please reset any member data you declared, as 4 // the same Solution instance will be reused for each test case. 5 if(str == null) 6 return 0; 7 if(str.length() == 0) 8 return 0; 9 str = str.trim(); 10 boolean positive = true; 11 long result = 0; 12 if(str.charAt(0) == '-') 13 { 14 str = str.substring(1); 15 positive = false; 16 } 17 else if(str.charAt(0) == '+') 18 { 19 str = str.substring(1); 20 } 21 for(int i=0;i<str.length();i++) 22 { 23 char tmp = str.charAt(i); 24 if(tmp >= '0' && tmp <= '9') 25 result = 10 * result + tmp - '0'; 26 else 27 break; 28 } 29 if(result > Integer.MAX_VALUE) 30 return positive?Integer.MAX_VALUE:Integer.MIN_VALUE; 31 return positive?(int)result:(int)(-1*result); 32 } 33 }
