Problem 4：Largest palindrome product

标签：枚举、回文数

原文：A palindromic number reads the same both ways. The largest palindrome made from the product of two $2$-digit numbers is $9009=91\times 99$.

Find the largest palindrome made from the product of two $3$-digit numbers.

翻译：回文数是指从前往后读和从后往前读都一样的数。由两个 $2$ 位数相乘得到的回文数中，最大的是 $9009=91\times 99$。

求最大的由两个 $3$ 位数相乘得到的回文数。

题解：直接枚举两个在 $100$ ~ $999$ 之间的数，对它们的乘积做一个回文数判定，数据范围比较小，可以直接数字翻转一下判断。

代码：

#include <bits/stdc++.h>
using namespace std;bool check(int a) {int b = a, c = 0;while (b > 0) {c = 10 * c + b % 10;b /= 10;}return c == a;
}int main() {int mx = 0;for (int i = 100; i <= 999; i++)for (int j = 100; j <= 999; j++) {if (check(i * j)) mx = max(mx, i * j);}cout << mx << endl;return 0;
}

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