Solution by coderGirl

[coderGirl]

Approach #1 [Accepted]

Algorithm

For this problem we have to take care of the following:

1. White spaces
2. Signs
3. Overflow

Java

public class Solution {
    public static int myAtoi(String str) {
        if(str.length()==0)
            return 0;
        StringBuilder sb=new StringBuilder();
        int sign=1,i=0;
        //removing leading white spaces
            while (str.charAt(i)==' ')
                i++;
        //taking care of signs
            if(str.charAt(i)=='+') {
                sign = 1;
                i++;
            }
            else if(str.charAt(i)=='-') {

                sign = -1;
                i++;
            }
            //extracting digits
            while(i<str.length()) {
                if(str.charAt(i)<'0'|| str.charAt(i)>'9') {
                    break;
                }
                else {
                    sb.append(str.charAt(i) - '0');
                }
                i++;
            }
        int total=0;
        for(char ch: sb.toString().toCharArray())
        {
            int digit=Integer.parseInt(ch+"");
            System.out.println(total);
            //handling the overflow case
            if(Integer.MAX_VALUE/10<total||Integer.MAX_VALUE/10==total && Integer.MAX_VALUE%10<digit )
            {
                return sign==1? Integer.MAX_VALUE:Integer.MIN_VALUE;
            }
            total=total*10+digit;
        }
        return total*sign;
    }
  }

Complexity Analysis

• Time complexity : O(n).