Design Hit Counter solution and explanation

class HitCounter:

    def __init__(self):
        self.ts = []

    def hit(self, timestamp: int) -> None:
        self.ts.append(timestamp)

    def getHits(self, timestamp: int) -> int:
        return len(self.ts) - bisect_left(self.ts, timestamp - 300 + 1)


# Your HitCounter object will be instantiated and called as such:
# obj = HitCounter()
# obj.hit(timestamp)
# param_2 = obj.getHits(timestamp)

class HitCounter {
    private List<Integer> ts = new ArrayList<>();

    public HitCounter() {
    }

    public void hit(int timestamp) {
        ts.add(timestamp);
    }

    public int getHits(int timestamp) {
        int l = search(timestamp - 300 + 1);
        return ts.size() - l;
    }

    private int search(int x) {
        int l = 0, r = ts.size();
        while (l < r) {
            int mid = (l + r) >> 1;
            if (ts.get(mid) >= x) {
                r = mid;
            } else {
                l = mid + 1;
            }
        }
        return l;
    }
}

/**
 * Your HitCounter object will be instantiated and called as such:
 * HitCounter obj = new HitCounter();
 * obj.hit(timestamp);
 * int param_2 = obj.getHits(timestamp);
 */

class HitCounter {
public:
    HitCounter() {

    }

    void hit(int timestamp) {
        ts.push_back(timestamp);
    }

    int getHits(int timestamp) {
        return ts.end() - lower_bound(ts.begin(), ts.end(), timestamp - 300 + 1);
    }

private:
    vector<int> ts;
};

/**
 * Your HitCounter object will be instantiated and called as such:
 * HitCounter* obj = new HitCounter();
 * obj->hit(timestamp);
 * int param_2 = obj->getHits(timestamp);
 */

class HitCounter {
    private ts: number[] = [];

    constructor() {}

    hit(timestamp: number): void {
        this.ts.push(timestamp);
    }

    getHits(timestamp: number): number {
        const search = (x: number) => {
            let [l, r] = [0, this.ts.length];
            while (l < r) {
                const mid = (l + r) >> 1;
                if (this.ts[mid] >= x) {
                    r = mid;
                } else {
                    l = mid + 1;
                }
            }
            return l;
        };
        return this.ts.length - search(timestamp - 300 + 1);
    }
}

/**
 * Your HitCounter object will be instantiated and called as such:
 * var obj = new HitCounter()
 * obj.hit(timestamp)
 * var param_2 = obj.getHits(timestamp)
 */

type HitCounter struct {
	ts []int
}

func Constructor() HitCounter {
	return HitCounter{}
}

func (this *HitCounter) Hit(timestamp int) {
	this.ts = append(this.ts, timestamp)
}

func (this *HitCounter) GetHits(timestamp int) int {
	return len(this.ts) - sort.SearchInts(this.ts, timestamp-300+1)
}

/**
 * Your HitCounter object will be instantiated and called as such:
 * obj := Constructor();
 * obj.Hit(timestamp);
 * param_2 := obj.GetHits(timestamp);
 */

struct HitCounter {
    ts: Vec<i32>,
}

/**
 * `&self` means the method takes an immutable reference.
 * If you need a mutable reference, change it to `&mut self` instead.
 */
impl HitCounter {
    fn new() -> Self {
        HitCounter { ts: Vec::new() }
    }

    fn hit(&mut self, timestamp: i32) {
        self.ts.push(timestamp);
    }

    fn get_hits(&self, timestamp: i32) -> i32 {
        let l = self.search(timestamp - 300 + 1);
        (self.ts.len() - l) as i32
    }

    fn search(&self, x: i32) -> usize {
        let (mut l, mut r) = (0, self.ts.len());
        while l < r {
            let mid = (l + r) / 2;
            if self.ts[mid] >= x {
                r = mid;
            } else {
                l = mid + 1;
            }
        }
        l
    }
}