1024. Palindromic Number 解析

和1023 一样  long long照样爆，自己写加法函数吧~~~~

#include <iostream>
#include <string>
#include <vector>
#include <stack>

using namespace std;

string N;
int K;

int char2int(char c) {
	return int(c - '0');
}

char int2char(int n) {
	return char('0' + n);
}

bool isPal(string s) {
	int len = s.size();
	for (int i = 0; i < len / 2; i++) {
		if (s[i] != s[len - i - 1])
			return false;
	}
	return true;
}

string Add(string s) {
	int len = s.size();
//	cout << "len " << len << endl;
	int carry = 0, digit = 0, sum = 0;
	string add;
	stack <char> st;

	for (int i = len -1 ; i >= 0 ; i--) {
		sum = char2int(s[i]) + char2int(s[len - i - 1]) + carry;
//		cout << sum << endl;
		digit = sum % 10;
		carry = sum / 10;
//		cout << "digit " << digit << " carry " << carry << endl;
		st.push(int2char(digit));
	}
	if (carry != 0) {
		st.push(int2char(carry));
	}
	while (!st.empty()) {
		add.push_back(st.top());
		st.pop();
	}
//	cout << add << endl;
	return add;
}


int main() {
	cin >> N >> K;
//	cout << N << " " << K << endl;
	
	int i = 0;
	for (i = 0; i < K; i++) {
		if (isPal(N)) {
			break;
		}
		else {
			N = Add(N);
//			cout << N << endl;
		}
	}

	cout << N << endl;
	cout << i << endl;

	system("pause");

	return 0;
}