LeetCode:Add Strings

最新推荐文章于 2018-09-04 15:50:33 发布

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最新推荐文章于 2018-09-04 15:50:33 发布

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分类专栏： LeetCode OJ LeetCode解题记录文章标签： LeetCode Math

本文链接：https://blog.youkuaiyun.com/itismelzp/article/details/52981475

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本文介绍了一种不使用内置大整数库或直接转换为整数的方法来实现两个大整数字符串相加的算法。该算法适用于长度不超过5100的大整数字符串，通过逐位相加并进位处理实现两数相加。

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Add Strings

Total Accepted: 9009
Total Submissions: 21652
Difficulty: Easy
Contributors: Admin

Given two non-negative numbers num1 and num2 represented as string, return the sum of num1 and num2.

Note:

The length of both num1 and num2 is < 5100.
Both num1 and num2 contains only digits 0-9.
Both num1 and num2 does not contain any leading zero.
You must not use any built-in BigInteger library or convert the inputs to integer directly.

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(M) Add Two Numbers (M) Multiply Strings

java code:

public class Solution {
    public static String addStrings(String num1, String num2) {

		StringBuffer sb = new StringBuffer();
		int i = num1.length() - 1, j = num2.length() - 1;
		int a, b;
		int c = 0;
		int sum;
		while (i >= 0 && j >= 0) {
			a = num1.charAt(i) - '0';
			b = num2.charAt(j) - '0';
			sum = a + b + c;
			sb.append(sum%10 +"");
			c = sum/10;
			i--;
			j--;
		}

		while (i >= 0) {
			sum = num1.charAt(i) - '0' + c;
			sb.append(sum%10 + "");
			c = sum/10;
			i--;
		}

		while (j >= 0) {
			sum = num2.charAt(j) - '0' + c;
			sb.append(sum%10 + "");
			c = sum/10;
			j--;
		}

		if(c!=0){
			sb.append(c+"");
		}
		
		sb.reverse();
		return sb.toString();
	}
}