移动0到数组末尾

只移动0，其他顺序不变；必须在元素组进行操作

会改变原数组内的值类型

const moveZeroByReg = (arr = [1,0,2,0,3,0,4,0,5]) => {
    const reg = /0/g
    let str = arr.join('')
    const res = str.match(reg)
    str = str.replace(reg, '')
    str += res.join('')
    arr = str.split('')
    return arr
}

使用splice 时间复杂度O(n^2)

const removeZeroBySplice = (arr = [1,0,2,0,3,0,4,0,5]) => {
    const { length } = arr
    let zeroCount = 0
    for(let i = 0; i < length - zeroCount; i++ ){
        if(arr[i] === 0){
            arr.splice(i,1)
            arr.push(0)
            i--
            zeroCount++
        }
    }
    return arr
}

　　双指针

const moveZeroByDoublePointer = (arr = [1,0,2,0,3,0,4,0,5]) => {
    const { length } = arr
    let firstZeroIndex = -1
    for(let i = 0; i < length; i++){
        const value = arr[i]
        if(value === 0){
            if(firstZeroIndex < 0){
                firstZeroIndex = i
            }
        }else {
            if(firstZeroIndex >= 0 ){
                arr[i] = 0
                arr[firstZeroIndex] = value
                firstZeroIndex++
            }
        }
    }
    return arr
}