【LeetCode】202. Happy Number

LeetCode-202

Links:https://leetcode.com/problems/happy-number/

Write an algorithm to determine if a number is “happy”.

A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the number equals 1 (where it will stay), or it loops endlessly in a cycle which does not include 1. Those numbers for which this process ends in 1 are happy numbers.

Example: 19 is a happy number

1² + 9² = 82
8² + 2² = 68
6² + 8² = 100
1² + 0² + 0² = 1

思路：首先默认1是HappyNum，然后判断当前数字是否出现过，如果没有，就进行一次计算，再判断是否出现过。出现过说明有循环出现了，则不会是HappyNum…

class Solution {
public:
    bool isHappy(int n) {
        map<int,bool>nums;
        nums[1] = true;
        while(1)
        {
            if(nums.find(n)==nums.end())
            {
                nums[n] = false;
                int count = 0;
                while(n){
                    int temp = n%10;
                    count += temp*temp;
                    n/=10;
                }
                n = count;
            }
            else{
                return nums[n];
            }
        }
    }
};

class Solution {

public:

bool isHappy(int n) {

map<int,bool>nums;

nums[1] = true;

while(1)

{

if(nums.find(n)==nums.end())

{

nums[n] = false;

int count = 0;

while(n){

int temp = n%10;

count += temp*temp;

n/=10;

}

n = count;

}

else{

return nums[n];

}

};

【LeetCode】202. Happy Number

Tagged on: LeetCode