Problem 4

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.


找到满足一下两个条件的数
1.回文数
2.由两个三位数相乘可得

//判断是否是回文数
	public static boolean is_palindrome(int number){
		String numStr = String.valueOf(number);
		char high =1; //保存最高位
		char low =1; //保存最低位
		do{
			high = numStr.charAt(0);
			low = numStr.charAt(numStr.length()-1);
			if(high!=low){
				return false;
			}
			numStr = numStr.substring(1,numStr.length()-1);
		}while(high==low&&numStr.length()>1);
		return true;
	}

	public int findLargestPalindrome(){
		int begin = 100;
		int end = 1000;
		int max = 0;
		for(int i=begin; i<end;i++){
			for(int j=begin; j<end; j++){
				int value = i*j;
				if(is_palindrome(value)&&value>max)
					max = value;
			}
		}
		return max;
	}