目录

两个大整数相加

lintcode 访问路径

http://www.lintcode.com/zh-cn/problem/big-integer-addition/

描述

给出两个非负整数num1num2的字符串形式,返回num1num2的和。

注意事项

  • 两个字符串num1num2的长度小于5100。
  • 两个字符串num1num2只包含0-9 (#)。
  • 两个字符串num1num2不会以0开头。
  • 不能使用任何整数类库,也不能将输入参数直接转换成整数。

样例

给出 num1 = "123",num2 = "45", 返回 "168"

Java代码实现

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public class Solution {
    /**
     * @param num1 a non-negative integers
     * @param num2 a non-negative integers
     * @return return sum of num1 and num2
     */
    public String addStrings(String num1, String num2) {
        // Write your code here
        int lena = num1.length() - 1;
        int lenb = num2.length() - 1;
        int temp = 0;
        String result = "";
        while (lena >= 0 || lenb >= 0) {
            int x = 0;
            int y = 0;
            if (lena >= 0) {
                x = num1.charAt(lena) - '0';
            }
            if (lenb >= 0) {
                y = num2.charAt(lenb) - '0';
            }
            int sum = x + y + temp;
            result = String.valueOf(sum % 10) + result;
            temp = sum / 10;
            lena = lena - 1;
            lenb = lenb - 1;
        }
        if (temp > 0) {
            result = String.valueOf(temp) + result;
        }
        return result;
    }
}

Python代码实现

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class Solution:
    # @param {string} num1 a non-negative integers
    # @param {string} num2 a non-negative integers
    # @return {string} return sum of num1 and num2
    def addStrings(self, num1, num2):
        # Write your code here
        lena = len(num1) - 1
        lenb = len(num2) - 1
        temp = 0
        result = ""
        while lena >= 0 or lenb >= 0:
            x = int(num1[lena]) if lena >= 0 else 0
            y = int(num2[lenb]) if lenb >= 0 else 0
            sum = x + y + temp
            result = str(sum % 10) + result
            temp = sum / 10
            lena, lenb = lena - 1, lenb - 1
        if temp > 0:
            result = str(temp) + result
        return result