代码挑战:幸福数字 - Javascript
【摘要】 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 ...
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:
Input: 19
Output: true
Explanation:
12 + 92 = 82
82 + 22 = 68
62 + 82 = 100
12 + 02 + 02 = 1
方案:
var isHappy = function (n) {
let set = new Set();
while (!set.has(n)) {
set.add(n);
let v = 0;
while (n > 0) {
v += Math.pow(n % 10, 2);
n = Math.floor(n / 10);
}
n = v;
}
return n == 1;
};
测试案例:
describe("isHappy()", function () {
it("test1", function () {
// 1. ARRANGE
let num = 19;
// 2. ACT
var result = isHappy(num);
// 3. ASSERT
expect(result).to.be.equal(true);
});
it("test2", function () {
// 1. ARRANGE
let num = 4;
// 2. ACT
var result = isHappy(num);
// 3. ASSERT
expect(result).to.be.equal(false);
});
it("test3", function () {
// 1. ARRANGE
let num = 123;
// 2. ACT
var result = isHappy(num);
// 3. ASSERT
expect(result).to.be.equal(false);
});
});
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