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2015.4.22 12:39
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
Solution:
Dull.
Accepted code:
1 @@ -0,0 +1,36 @@ 2 // 1CE, 1AC, dull 3 #include <unordered_set> 4 using namespace std; 5 6 class Solution { 7 public: 8 bool isHappy(int n) { 9 unordered_set<int> us; 10 unordered_set<int>::iterator it; 11 12 while (true) { 13 if (n == 1) { 14 break; 15 } 16 if (us.find(n) == us.end()) { 17 us.insert(n); 18 } else { 19 break; 20 } 21 n = dsum(n); 22 } 23 return n == 1; 24 } 25 private: 26 int dsum(int n) { 27 int s = 0; 28 int d; 29 while (n > 0) { 30 d = n % 10; 31 n /= 10; 32 s += d * d; 33 } 34 35 return s; 36 } 37 };
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原文地址：http://www.cnblogs.com/zhuli19901106/p/4447124.html
