public class Solution {
  public int myAtoi(String str) {
    if ("".equals(str)) {return 0;}
    int i = 0, sign = 1, length = str.length();
    double base = 0;
    while (str.charAt(i) == ' ') {i++;}
    if (str.charAt(i) == '-' || str.charAt(i) == '+') {
      sign = str.charAt(i++) == '-' ? -1 : 1;
    }
    while (i < length && str.charAt(i) >= '0' && str.charAt(i) <= '9') {
      if ((base = base * 10 + (str.charAt(i++) - '0')) > Integer.MAX_VALUE) {
        return sign == 1 ? Integer.MAX_VALUE : Integer.MIN_VALUE;
      }
    }
    return sign * (int)base;
  }
}