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HTML

              
                
              
            
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CSS

              
                
              
            
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JS

              
                // 請寫出一個 function isPrime,給定一個數字 n,回傳 n 是否為質數。
// (質數的定義:除了 1 以外,沒辦法被所有 < n 的正整數整除)
// isPrime(1) 正確回傳值:false
// isPrime(5) 正確回傳值:true
// isPrime(37) 正確回傳值:true

function isPrime(n) {
    // 例外處理
    if ( n === 1 || n === 0 ) return false
    
    // 撇除例外,判定n是否能被2~n以內的數整除,不行就是質數
    for (let i=2; i<=Math.sqrt(n); i++) {
        if ( n % i === 0 ) {
            return false
        }
    }
    return true
}

console.log(isPrime(1))
console.log(isPrime(5))
console.log(isPrime(37))
              
            
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