https://www.acwing.com/problem/content/793/
#include<bits/stdc++.h> using namespace std; vector<int> add(vector<int> &A, vector<int> &B) { vector<int> C; int t = 0; for (int i = 0; i < A.size()||i < B.size(); i ++ ) { if(i<A.size()) t+=A[i]; if(i<B.size()) t+=B[i]; C.push_back(t % 10); t /= 10; } if (t) C.push_back(1); return C; } int main() { string a,b; vector<int>A,B; cin>>a>>b;//a=123456 for(int i=a.size()-1; i>=0; i--) A.push_back(a[i]-‘0‘); for(int i=b.size()-1; i>=0; i--) B.push_back(b[i]-‘0‘); auto C=add(A,B); for(int i=C.size()-1; i>=0; i--) printf("%d",C[i]); return 0; }