题目

---

 

 

 

代码部分一（3ms 92.36%）

class Solution {
    public boolean isHappy(int n) {
        Set<Integer> set = new HashSet<>();
        while(n != 1 && !set.contains(n)){
            set.add(n);
            int sum = 0;
            while(n > 0){
                sum += (n % 10) * (n % 10);
                n /= 10;
            }
            n = sum;
        }
        return  n == 1;        

    }
}

 

代码部分二(3ms 92.36%)

class Solution {
    public boolean isHappy(int n) {
     while (n != 1 && n != 4) {
            int t = 0;
            while (n!=0) {
                t += (n % 10) * (n % 10);
                n /= 10;
            }
            n = t;
        }
        return n == 1;
        
    }
}

 

代码部分三（0ms 100%)

class Solution {
    public boolean isHappy(int n) {
        if(n < 10) {
            return n == 1 || n == 7;
        }
        int sum = n;
        int b = 0;
        while(sum > 0) {
            b += (sum % 10) * (sum % 10);
            sum = sum / 10;
        }
        return isHappy(b);

    }
}