p415

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LeetCode p415 Add Strings 题解

1.题目：

Given two non-negative integers 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.

题意：

输入两个数字的字符串，返回他们相加的和。

2.解题思路:

见代码

3.代码

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public class Solution {
    public String addStrings(String num1, String num2) {
        StringBuilder sBuilder = new StringBuilder();

		int len1 = num1.length() - 1;
		int len2 = num2.length() - 1;
		int c = 0;
		for (; len1 >= 0 || len2 >= 0; len1--, len2--) {

			int i = c;
			if (len1 >= 0)
				i += num1.charAt(len1) - '0';
			if (len2 >= 0)
				i += num2.charAt(len2) - '0';
			c = i / 10;
			i = i % 10;
			char a = (char) ('0' + i);
			sBuilder.append(a);
		}

		if (c > 0)
			sBuilder.append((char) ('0' + c));
		return sBuilder.reverse().toString();
    }
}

4.一些总结：