1.The Feast of Many Beasts
/**
判断两个字符串首尾字符是否一致
*/
// 获取首尾字符直接判断
function feast(beast, dish) {return beast[0] === dish[0] && beast[beast.length-1] === dish[dish.length-1]
}
// slice substr startsWith 等方法均可以达到目的
function feast(beast, dish) {return beast.charAt(0)===dish.charAt(0)&&beast.substr(-1)===dish.substr(-1)
}
}
2.The Supermarket Queue
/**
超市排队结算,第一个参数为序列数组,元素表示时长,第二个参数为收银台的个数,不允许插队。计算出所有人结算的时间。思路:要计算最后的时间,就要比较得出耗时最长的收银台。可以定义数组存放每个收银台的耗时,初始都为 0,长度为 n。然后将 customers 数组的第一个元素依次放入 arr,优先放到值最小的位置。*/
function queueTime(customers, n) {
//TODO
if(customers.length <= 0) return 0
let arr = new Array(n);
arr.fill(0);
do {arr[arr.indexOf(Math.min.apply(null, arr))] += customers.shift()} while (customers.length > 0)
return Math.max.apply(null, arr)
}
// 优化以后,对 customers 遍历,并将值保存到合适的位置;使用扩展运算符计算最大最小值
function queueTime(customers, n) {let arr = new Array(n).fill(0);
for (let i of customers) {arr[arr.indexOf(Math.min(...arr))] += i;
}
return Math.max(...arr);
}
3.Build a Car
/**
设计一个 Car 构造函数,它的 body 属性、chassis 属性都是对象,均有一个 component 属性,存放表示三层的字符串。第一层是 ""+"_".repeat(n) 这样的字符串,长度为 length-2;第二层是 "|" + "[]".repeat(n) + "".repeat(n) +"[]".repeat(n) +"\\" 这样的字符串,长度为 length-1;第三层是 "-o".repeat(n) + "-".repeat(n) + "o-".repeat(n) + "'" 这样的字符串,长度为 length。_____________ ______ __________
|[][] [][][]\ |[][][]\ | []\
-o-o-o-----o-o-'-o----o-' -o-o------o-'
实例化时传入 length 和 doors 两个实参,构造函数的基础形式如下。需要计算出 first、second、third 三个字符串,其实就是计算要多少
function Car(length, doors) {if(length<7 || doors === 0 || doors*2 > length-3){throw new Error()
}
let first = second = third = ""
this.body = {component: first + "\n" + second + "\n"}
this.chassis = {component: third}
}
// first, 这个很简单,只有 "_" 会变化
first = ''+'_'.repeat(length-3)
// second, 主要是计算 "[]" 的左右位置的个数,左右总是相等或者左比右小一,所以用数组来存放然后根据 doors/2 来计算
let secondDoors = ['[]'.repeat(doors/2|0),'[]'.repeat(Math.ceil(doors/2))];
second = "|" + secondDoors[0] + "".repeat(length-3-doors*2) + secondDoors[1] +"\\";
//third,主要是轮子的个数及位置
let axlesElse = length-12 > 0 ? Math.floor((length-12)/2)+1 : 0;
for(let i = 0; i < axlesElse; i++){thirdAxles[(i%2)]+="o-"
}
let third = thirdAxles[0] + '-'.repeat(length-1-2*axlesElse-3*2) + thirdAxles[1] + "'";
*/
// 最后简化
function Car(length, doors) {if(length<7 || doors === 0 || doors*2 > length-3){throw new Error()
}
let thirdAxles = ["-o-","-o-"];
let axlesElse = length-12 > 0 ? Math.floor((length-12)/2)+1 : 0;
for(let i = 0; i < axlesElse; i++){thirdAxles[(i%2)]+="o-"
}
let third = thirdAxles[0] + '-'.repeat(length-1-2*axlesElse-3*2) + thirdAxles[1] + "'";
this.body = {component: "" +"_".repeat(length-3) +"\n|"+'[]'.repeat(doors/2|0) +" ".repeat(length-3-doors*2) +'[]'.repeat(Math.ceil(doors/2)) +"\\\n"
}
this.chassis = {component: thirdAxles[0] + '-'.repeat(length-1-2*axlesElse-3*2) + thirdAxles[1] + "'"
}
}