本章主要學習如何透過演算法學習訓練思考

Palindrome BigO(n)

檢查是否reverse也是相同的
EX: anna = anna

function Palindrome(str){
    let left = 0
    let right = str.length -1
    
    while(left <= right){
        if(str[left] === str[right]){
            left++
            right--
        }else{
            return false
        }
    }return true
}
console.log(Palindrome('hcco')) //false

Subsequence

檢查是否為子序列

function subsequence(str1, str2){ //str1為原始序列, str2為子序列
    if(str1.length == 0 ){
        return true
    }
    let pointer1 = 0 //設置兩個指標,逐一比對
    let pointer2 = 0

    while(str2.length > pointer2){
        if(str1[pointer1] == str2[pointer2]){ //若str1 == str2 str1[pointer] ++ 繼續比對
            pointer1++
        }
        if(pointer1 >= str1.length){
            return true //如果pointer已經 == str1長度 代表都符合 即回傳true
        }
        pointer2++ //每次執行都要比對str2[pointer] 所以++
    }return false ///若都不符合即回傳false
}
console.log(subsequence("hello", "hssello")) //true
console.log(subsequence("hello", "ehllo"))  //false