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AddStrings.cpp
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48 lines (42 loc) · 1.46 KB
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// Source : https://leetcode.com/problems/add-strings/
// Author : Hao Chen
// Date : 2016-11-12
/***************************************************************************************
*
* 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
* 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.
***************************************************************************************/
class Solution {
public:
string addStrings(string num1, string num2) {
string& longstr = ( num1.size() >= num2.size() ? num1 : num2 );
string& shortstr = ( num1.size() < num2.size() ? num1 : num2 );
int longlen = longstr.size();
int shortlen = shortstr.size();
char carry = 0;
int i, j;
string result;
for (i = longlen-1, j=shortlen-1; i>=0; i--, j--) {
int add = 0;
if (j>=0) {
add = longstr[i] + shortstr[j] - 2 * '0' + carry;
}else{
add = longstr[i] - '0' + carry;
}
carry = add/10;
result = char('0' + add % 10) + result;
}
if (carry) {
result = '1' + result;
}
return result;
}
};