首先涉及10位数字相加，考虑用大整数运算了，注意字符串赋值不能直接一个一个赋值，要采取拼接+s 或者赋值一个一个替换，因为要提前知道大小。
然后注意大整数加法运算。
#include<iostream>
#include<vector>
#include<map>
#include<string>
#include<cstring>
#include<cstdio>
#include<algorithm>
#include<set>
#include<queue>
#include<unordered_set>
using namespace std;
bool ishuiwen(string s)
{int j = s.size() - 1;for (int i = 0; i < s.size()&&i<j; i++,j--){if (s[i] != s[j])return false;}return true;
}
int main()
{string ss,s1,s2; cin >> ss;int cnt = 0;string ans; while (!ishuiwen(ss)){int len = 0;s1 = ss;s2 = ss;reverse(s1.begin(), s1.end());int length = ss.length(), carry = 0;for (int i = length-1; i >=0; i--){int num = (s1[i] - '0' + ss[i] - '0') + carry;s2[len++] = num % 10 + '0';carry = num / 10;}if (carry != 0){s2+= (carry + '0'); //这里不能直接赋值 要字符串相加}reverse(s2.begin(), s2.end());cout << ss << " + " << s1 << " = " << s2<< endl;ss = s2;cnt++;if (cnt == 10)break;}if (cnt < 10){cout << ss << " is a palindromic number." << endl;}else{cout << "Not found in 10 iterations." << endl;}
}