题解 | #反序数#

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

using namespace std;

int main() {
	int reverse_n;
	for (int i = 1000; i < 1111; i++)
	{
		reverse_n = i * 9;
		if (reverse_n/1000==i%10)
		{
			if ((reverse_n/100)%10==(i%100)/10)
			{
				if ((reverse_n%100)/10== (i % 100) / 100)
				{
					if (reverse_n%10==i/1000)
					{
						cout << i << endl;

					}
				}
			}
		}

	}
}

本题关键在于：如何Reverse

Question：求一个数x的反序数

int Reverse(int x) {
	int revx = 0;
	while (x != 0) {
		revx *= 10;
		revx += x % 10;
		x /= 10;
	}
	return x;
}

改进后的代码

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

using namespace std;

int Reverse(int x) {
	int revx = 0;
	while (x != 0) {
		revx *= 10;
		revx += x % 10;
		x /= 10;
	}
	return revx;
}
int main() {
	int reverse_n;
	for (int i = 1000; i < 1111; i++)
	{
		reverse_n = i * 9;
		int reverse_i = Reverse(i);
		if (reverse_i==reverse_n)
		{
			cout << i << endl;
		}

	}
}