- 将java代码改为js的过程中,该题我用数组排序sort方法,提交报超时,改成大顶堆就过了,就是写起来费事.
/**
* @param {number[][]} courses
* @return {number}
*/
class BigHeap {
constructor() {
this.heap = []
}
getParentIndex(i) {
// return Math.floor((i - 1) / 2)
return (i - 1) >> 1
}
getLeftIndex(i) {
return (i * 2) + 1
}
getRightIndex(i) {
return (i * 2) + 2
}
shiftDown(index) {
const leftIndex = this.getLeftIndex(index)
const rightIndex = this.getRightIndex(index)
if(this.heap[leftIndex] > this.heap[index]){
this.swap(leftIndex,index)
this.shiftDown(leftIndex)
}
if(this.heap[rightIndex] > this.heap[index]) {
this.swap(rightIndex,index)
this.shiftDown(rightIndex)
}
}
shiftUp(index) {
if (index == 0) return
const parentIndex = this.getParentIndex(index)
if (this.heap[parentIndex] < this.heap[index]) {
this.swap(parentIndex, index)
this.shiftUp(parentIndex)
}
}
swap(i1, i2) {
const temp = this.heap[i1]
this.heap[i1] = this.heap[i2]
this.heap[i2] = temp
}
insert(value) {
this.heap.push(value)
this.shiftUp(this.heap.length - 1)
}
// 删除
pop() {
const t = this.heap[0]
if(this.size() == 1) {
this.heap = []
return t
}
this.heap[0] = this.heap.pop()
this.shiftDown(0)
return t
}
// 获取堆顶
peek() {
return this.heap[0]
}
size() {
return this.heap.length
}
}
var scheduleCourse = function (courses) {
let arr = courses.sort((a, b) => a[1] - b[1])
let heap = new BigHeap() // 花费时间大根堆
let time = 0;
for (let c of courses) {
if (time + c[0] <= c[1]) {
// 当前时间 + 花费<= 截止时间
time += c[0]
heap.insert(c[0])
} else {
if (heap.size() != 0 && heap.peek() > c[0]) {
time -= heap.peek();
heap.pop()
heap.insert(c[0])
time += c[0]
}
}
}
return heap.size()
};
java版本:
package class51;
import java.util.Arrays;
import java.util.PriorityQueue;
public class Problem_0630_CourseScheduleIII {
public static int scheduleCourse(int[][] courses) {
// courses[i] = [花费时间,截止时间]
Arrays.sort(courses, (a, b) -> a[1] - b[1]);
// 花费时间的大根堆
PriorityQueue<Integer> heap = new PriorityQueue<>((a,b) -> b - a)
// 时间点
int time = 0;
for(int[] c : courses) {
if(time + c[0] <= c[1]) {
// 当前时间 + 花费时间 <= 截止时间
heap.add(c[0])
time += c[0]
}else {
// 当前时间 + 花费时间 > 截止时间的,只有淘汰掉某课程,当前的课程才能进来
if(!heap.isEmpty() && heap.peek() > c[0]) {
time -= heap.poll();
heap.add(c[0])
time += c[0]
}
}
}
return heap.size()
}
}
`
