leetcode 479. Largest Palindrome Product 最大的回文数字 + 直接暴力真好

╰+攻爆jí腚メ 2022-06-03 00:18 149阅读 0赞

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

Since the result could be very large, you should return the largest palindrome mod 1337.

Example:

Input: 2

Output: 987

Explanation: 99 x 91 = 9009, 9009 % 1337 = 987

Note:

The range of n is \[1,8\].

想了好久才明白直接遍历所有的可能即可

建议和[leetcode 680. Valid Palindrome II 去除一个字符的回文字符串判断 + 双指针][leetcode 680. Valid Palindrome II _ _] 一起学习

代码如下：

#include <iostream>
    #include <vector>
    #include <map>
    #include <unordered_map>
    #include <set>
    #include <unordered_set>
    #include <queue>
    #include <stack>
    #include <string>
    #include <climits>
    #include <algorithm>
    #include <sstream>
    #include <functional>
    #include <bitset>
    #include <numeric>
    #include <cmath>
    #include <regex>
    #include <iomanip>
    #include <cstdlib>
    #include <ctime>
    
    using namespace std;
    
    
    class Solution
    {
    public:
        int largestPalindrome(int n)
        {
            if (n == 1)
                return 9;
    
            int maxNum = pow(10, n), minNum = pow(10, n - 1);
            for (int i = maxNum; i >= minNum; i--)
            {
                string a = to_string(i), b = a;
                reverse(b.begin(), b.end());
                long long now = stoll(a + b);
                for (int j = maxNum; j >= minNum; j--)
                {
                    if (now / j >= maxNum)
                        break;
                    else if (now%j == 0)
                        return now % 1337;
                }
            }
            return -1;
        }
    };

[leetcode 680. Valid Palindrome II _ _]: http://blog.csdn.net/jackzhang_123/article/details/78880022