package leetcode.string;

/**

* @ClassName AddStrings

* @Description 字符串相加

* @Author changxuan

* @Date 2020/8/3 下午8:24

**/

public class AddStrings {

public String addStrings(String num1, String num2) {

int i = num1.length() - 1, j = num2.length() - 1, tag = 0;

StringBuilder result = new StringBuilder();

char[] num1Char = num1.toCharArray();

char[] num2Char = num2.toCharArray();

while (i >=0 || j >=0 || tag > 0){

int up = i >= 0 ? num1Char[i--] - '0' : 0;

int down = j >= 0 ? num2Char[j--] - '0' : 0;

int temp = up + down + tag;

tag = temp / 10;

result.append(temp%10);

}

return result.reverse().toString();

}

}