代码随想录| Day 11 | 数组part 03 | 239. 滑动窗口最大值 | 347. 前 K 个高频元素

239. 滑动窗口最大值

var maxSlidingWindow = function (nums, k) {
    class MonoQueue {
        queue;
        constructor() {
            this.queue = [];
        }
        enqueue(value) {
            let back = this.queue[this.queue.length - 1];
            while (back !== undefined && back < value) {
                this.queue.pop();
                back = this.queue[this.queue.length - 1];
            }
            this.queue.push(value);
        }
        dequeue(value) {
            let front = this.front();
            if (front === value) {
                this.queue.shift();
            }
        }
        front() {
            return this.queue[0];
        }
    }
    let helperQueue = new MonoQueue();
    let i = 0, j = 0;
    let resArr = [];
    while (j < k) {
        helperQueue.enqueue(nums[j++]);
    }
    resArr.push(helperQueue.front());
    while (j < nums.length) {
        helperQueue.enqueue(nums[j]);
        helperQueue.dequeue(nums[i]);
        resArr.push(helperQueue.front());
        i++, j++;
    }
    return resArr;
};

347. 前 K 个高频元素

var topKFrequent = function(nums, k) {
    let hashMap = new Map()
    let res = []
    for(let i =0;i<nums.length;i++){
        if(hashMap.has(nums[i])){
            hashMap.set(nums[i],hashMap.get(nums[i])+1)
        }else{
            hashMap.set(nums[i],1)
        }
    }
     let sortArray = Array.from(hashMap).sort((a, b) => b[1] - a[1]);
    for(let i = 0; i < k; i++) {
        res.push(sortArray[i][0]);
    }
    return res;


};