欧拉计划第４题

 

Problem 4

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Largest palindrome product

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

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

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最大回文乘积

回文数就是从前往后和从后往前读都一样的数。由两个2位数相乘得到的最大回文乘积是 9009 = 91 × 99。

找出由两个3位数相乘得到的最大回文乘积。

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代码演示

#include <iostream>
using namespace std;
int is_valid(int x){
	int raw=x,temp=0;
	while(x){
		temp=temp*10+x%10;
		x/=10;
	}
return temp==raw;
}
int main(){
	int ans=0;
	for(int i=0;i<1000;i++){
		for(int j=i;j<1000;j++){
			if(is_valid(i*j) && i*j>ans) ans=i*j;
		}
	}
	printf("%d\n",ans);
	return 0;
}

答案

906609