程序師世界是廣大編程愛好者互助、分享、學習的平台,程序師世界有你更精彩!
首頁
編程語言
C語言|JAVA編程
Python編程
網頁編程
ASP編程|PHP編程
JSP編程
數據庫知識
MYSQL數據庫|SqlServer數據庫
Oracle數據庫|DB2數據庫
 程式師世界 >> 編程語言 >> C語言 >> C++ >> 關於C++ >> [LeetCode202] Happy Number

[LeetCode202] Happy Number

編輯:關於C++

 

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

    Solution:

    use loop to calcuate the square sum until meet one of these two stops:

    1. sum is 1, return true

    2. sum value got before, which means there is a sum loop and will never goes to 1. return false

     

     

    public boolean isHappy(int n) {
            if(n<=0) return false;
            Set records = new HashSet<>();
            long ln = n;
            while(ln< Integer.MAX_VALUE){
                if(records.contains(ln)) return false;
                else records.add(ln);
                ln = getSquareSum(ln);
                if(ln == 1) return true;
            }
            return false;
        }
        public long getSquareSum(long n){
            long sum = 0;
            while(n!=0){
                sum+= Math.pow(n%10,2);
                n/=10;
            }
            return sum;
        }


     

     

     

  1. 上一頁:
  2. 下一頁:
Copyright © 程式師世界 All Rights Reserved