20/11/15 20:20:51.56 8j4ATkh0.net
>>964 JavaScript
let hits = 0
const input = '曇,晴,曇,曇,晴,曇,曇,雨,雨,雨,曇,曇,晴,曇,雨,曇,雨,曇,曇,曇,晴,曇,雨,晴,晴,晴,晴,曇,晴,曇,晴'.split `,`
input.reduce((acc, v) => (hits += acc == v ? 1 : 0, v))
console.log(hits / (input.length - 1))
//=> 0.3333333333333333