202. 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
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12 + 92 = 82
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82 + 22 = 68
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62 + 82 = 100
-
12 + 02 + 02 = 1
思路：
采用set来判断容器中是否有该元素出现过，如果出现过，那么就形成了环状，结果返回false。否则找到快乐数字。返回true。
代码如下：
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class
Solution {
public
:
bool
isHappy(
int
n) {
set<
int
> myset;
int
total = 0;
while
(n != 1)
{
while
(n)
{
total += (n%10)*(n%10);
n /= 10;
}
if
(total == 1)
return
true
;
if
(myset.find(total) != myset.end())
return
false
;
else
myset.insert(total);
n = total;
total = 0;
}
return
true
;
}
};
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关于set容器的使用练习。
本文转自313119992 51CTO博客，原文链接:http://blog.51cto.com/qiaopeng688/1837555
