1、题目描述
2、问题分析
直接按照加法运算规则运算即可，注意进位问题。
3、代码
string addStrings(string num1, string num2) {
if( num1.empty() ) return num2;
if( num2.empty() ) return num1;
string::reverse_iterator it1 = num1.rbegin() ;
string::reverse_iterator it2 = num2.rbegin() ;
string s ;
int up = ;
while( it1 != num1.rend() && it2 != num2.rend() ){
int a = (*it1 - '') + (*it2 - '') + up ;
if( a < ){
s = std::to_string( a ) + s;
up = ;
}else{
s = std::to_string( a - ) + s;
up = ;
}
++it1;
++it2;
}
while( it1 != num1.rend() ){
if( *it1 - '' + up < ){
s = std::to_string( *it1 - '' + up ) + s;
up = ;
}else{
s = std::to_string( *it1 - '' + up - ) + s;
up = ;
}
++it1;
}
while( it2 != num2.rend() ){
if( *it2 - '' + up < ){
s = std::to_string( *it2 - '' + up ) + s;
up = ;
}else{
s = std::to_string( *it2 - '' + up - ) + s;
up = ;
}
++it2 ;
}
if( up == ){
s = std::to_string() + s;
}
return s;
}