LC.P729[我的日程安排表I]

方法一：模拟

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
class MyCalendar {

    List<int[]> booked;

    public MyCalendar() {
        booked = new ArrayList<int[]>();
    }

    public boolean book(int start, int end) {
        for (int[] arr : booked) {
            int left = arr[0], right = arr[1];
            if (left < end && start < right) {
                return false;
            }
        }
        booked.add(new int[]{start, end});
        return true;
    }
}

/**
 * Your MyCalendar object will be instantiated and called as such:
 * MyCalendar obj = new MyCalendar();
 * boolean param_1 = obj.book(start,end);
 */
  • 时间复杂度：$O(n^2)$
  • 空间复杂度：$O(n)$

方法二：线段树(动态开点)

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
class MyCalendar {

    public MyCalendar() {

    }
    
    public boolean book(int start, int end) {
        // 先查询该区间是否为 0
        if (query(root, 0, N, start, end - 1) != 0) return false;
        // 更新该区间
        update(root, 0, N, start, end - 1, 1);
        return true;
    }

    private int N = (int) 1e9;
    private Node root = new Node();

    public void update(Node node, int start, int end, int l, int r, int val) {
        if (l <= start && end <= r) {
            node.val += val;
            node.add += val;
            return ;
        }
        pushDown(node);
        int mid = (start + end) >> 1;
        if (l <= mid) update(node.left, start, mid, l, r, val);
        if (r > mid) update(node.right, mid + 1, end, l, r, val);
        pushUp(node);
    }

    public int query(Node node, int start, int end, int l, int r) {
        if (l <= start && end <= r) return node.val;
        pushDown(node);
        int mid = (start + end) >> 1, ans = 0;
        if (l <= mid) ans = query(node.left, start, mid, l, r);
        if (r > mid) ans = Math.max(ans, query(node.right, mid + 1, end, l, r));
        return ans;
    }

    private void pushUp(Node node) {
        // 每个节点存的是当前区间的最大值
        node.val = Math.max(node.left.val, node.right.val);
    }

    private void pushDown(Node node) {
        if (node.left == null) node.left = new Node();
        if (node.right == null) node.right = new Node();
        if (node.add == 0) return;
        node.left.val += node.add;
        node.right.val += node.add;
        node.left.add += node.add;
        node.right.add += node.add;
        node.add = 0;
    }
    
    private static class Node {
        // 左右孩子节点
        Node left, right;
        // 当前节点值，以及懒惰标记的值
        int val, add;
    }
}

/**
 * Your MyCalendar object will be instantiated and called as such:
 * MyCalendar obj = new MyCalendar();
 * boolean param_1 = obj.book(start,end);
 */
  • 时间复杂度：$O(logn)$
  • 空间复杂度：$O(mlogn)$，$m$为查询次数