q415-String-Add.md

Idea Vertical add. Firstly add for the align digits and then add for the extra digits

Code

class Solution { public String addStrings(String num1, String num2) { StringBuffer result = new StringBuffer(); int l1 = num1.length(); int l2 = num2.length(); int short_length; if (l1 > l2){ short_length = l2; } else{ short_length = l1; } int add = 0; int i1 = l1-1; int i2 = l2-1; // same digit add for (int i = short_length-1; i >= 0; i--){ int x = num1.charAt(i1) - '0'; int y = num2.charAt(i2) - '0'; int add_result = x + y + add; result.append(add_result % 10); add = add_result / 10; i1 --; i2 --; }

    //complete extra digits
    if (l1 > l2){
        while (i1 >= 0){
            int add_result = num1.charAt(i1)-'0' + add;
            result.append(add_result % 10);
            add = add_result / 10;
            i1--;
        }
    } else if (l1 < l2){
        while (i2 >= 0) {
            int add_result = num2.charAt(i2)-'0' + add;
            result.append(add_result % 10);
            add = add_result / 10;
            i2--;
        }
    }

    if (add > 0){
        result.append(1);
    }
    return result.reverse().toString();
}

}

作者：goofy-i2hodesqsi 链接：https://leetcode.cn/problems/add-strings/solution/415-string-add-java-by-goofy-i2hodesqsi-4l4d/ 来源：力扣（LeetCode） 著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。

作者：goofy-i2hodesqsi 链接：https://leetcode.cn/problems/add-strings/solution/415-string-add-java-by-goofy-i2hodesqsi-4l4d/ 来源：力扣（LeetCode） 著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。