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Add Strings

描述

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.

分析

这题与 Add Binary 一模一样,将它的代码中的 2 改为 10 即可。

代码

// Add Strings
// Time Complexity: O(max(m,n)), Space Complexity: O(max(m,n))
class Solution {
public String addStrings(String num1, String num2) {
StringBuilder result = new StringBuilder();
int i = num1.length() - 1, j = num2.length() - 1, carry = 0;
while(i >= 0 || j >= 0 || carry > 0) {
int x = i < 0 ? 0 : num1.charAt(i--) - '0';
int y = j < 0 ? 0 : num2.charAt(j--) - '0';
int sum = x + y + carry;
result.append(sum % 10);
carry = sum / 10;
}
return result.reverse().toString();
}
};

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