LeetCode----8. String to Integer (atoi)(Java) 

 1 package myAtoi8;
 2 /*
 3  * Implement atoi to convert a string to an integer.
 4 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.
 5 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.
 6 Update (2015-02-10):
 7 The signature of the C++ function had been updated. If you still see your function signature accepts a const char * argument, please click the reload button  to reset your code definition.
 8 */
 9 
10 public class Solution {
11     public static int myAtoi(String str) {
12         StringBuilder sb=new StringBuilder();
13         int flag=0;
14         if(str.length()==0)
15             return 0;
16         else{
17             for(int i=0;i<str.length();i++){
18                 if(str.charAt(i)<'0'||str.charAt(i)>'9')
19                     if(str.charAt(i)=='0'||str.charAt(i)==' ')
20                         if (sb.length()==0)
21                             continue;
22                         else
23                             break;
24                     else if (str.charAt(i)=='-')
25                         if (flag==0){
26                             flag=-1;
27                             sb.append('0');
28                         }
29                         else
30                             break;
31                     else if (str.charAt(i)=='+')
32                         if (flag==0){
33                             flag=1;
34                             sb.append('0');
35                         }
36                         else
37                             break;
38                     else
39                         break;
40                 else
41                     sb.append(str.charAt(i));        
42                 }        
43         }
44         if(sb.length()==0)
45             return 0;
46         else if(sb.length()>12)
47             str=sb.substring(sb.length()-12);
48         else
49             str=sb.toString();
50         if (flag==-1)
51             str="-"+str;
52         long result=Long.parseLong(str);
53         System.out.println(result);
54         if (result>2147483647)
55             return 2147483647;
56         else if (result<-2147483648)
57             return -2147483648;
58         else
59             return (int)result;
60         
61     }
62     public static void main(String[] args){
63         String str1="";//0
64         String str2="+";//0
65         String str3="              +45555";//45555
66         String str4="              -45555";//-45555
67         String str5="2147483647";//2147483647
68         String str6="2147483648";//2147483647
69         String str7="+-2";//0
70         String str8="-+2";//0
71         String str9="++2";//0
72         String str10="-2147483648";//-2147483648
73         String str11="   - 321";//0
74         String str12="      -11919730356x";//-2147483648
75         String str13="1234567890123456789012345678901234567890";//2147483647
76         System.out.println(myAtoi(str1));
77         System.out.println(myAtoi(str2));
78         System.out.println(myAtoi(str3));
79         System.out.println(myAtoi(str4));
80         System.out.println(myAtoi(str5));
81         System.out.println(myAtoi(str6));
82         System.out.println(myAtoi(str7));
83         System.out.println(myAtoi(str8));
84         System.out.println(myAtoi(str9));
85         System.out.println(myAtoi(str10));
86         System.out.println(myAtoi(str11));
87         System.out.println(myAtoi(str12));
88         System.out.println(myAtoi(str13));
89 
90 
91     }
92 }

 

posted @ 2016-09-13 21:28  蒲公英的花朵  阅读(368)  评论(0)    收藏  举报