[Swift]LeetCode1172. 餐盘栈 | Dinner Plate Stacks

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You have an infinite number of stacks arranged in a row and numbered (left to right) from 0, each of the stacks has the same maximum capacity.

Implement the DinnerPlates class:

DinnerPlates(int capacity) Initializes the object with the maximum capacity of the stacks.
void push(int val) pushes the given positive integer val into the leftmost stack with size less than capacity.
int pop() returns the value at the top of the rightmost non-empty stack and removes it from that stack, and returns -1 if all stacks are empty.
int popAtStack(int index) returns the value at the top of the stack with the given index and removes it from that stack, and returns -1 if the stack with that given index is empty.

Example:

Input: 
["DinnerPlates","push","push","push","push","push","popAtStack","push","push","popAtStack","popAtStack","pop","pop","pop","pop","pop"]
[[2],[1],[2],[3],[4],[5],[0],[20],[21],[0],[2],[],[],[],[],[]]
Output: 
[null,null,null,null,null,null,2,null,null,20,21,5,4,3,1,-1]

Explanation: 
DinnerPlates D = DinnerPlates(2);  // Initialize with capacity = 2
D.push(1);
D.push(2);
D.push(3);
D.push(4);
D.push(5);         // The stacks are now:  2  4
                                           1  3  5
                                           ﹈ ﹈ ﹈
D.popAtStack(0);   // Returns 2.  The stacks are now:     4
                                                       1  3  5
                                                       ﹈ ﹈ ﹈
D.push(20);        // The stacks are now: 20  4
                                           1  3  5
                                           ﹈ ﹈ ﹈
D.push(21);        // The stacks are now: 20  4 21
                                           1  3  5
                                           ﹈ ﹈ ﹈
D.popAtStack(0);   // Returns 20.  The stacks are now:     4 21
                                                        1  3  5
                                                        ﹈ ﹈ ﹈
D.popAtStack(2);   // Returns 21.  The stacks are now:     4
                                                        1  3  5
                                                        ﹈ ﹈ ﹈ 
D.pop()            // Returns 5.  The stacks are now:      4
                                                        1  3 
                                                        ﹈ ﹈  
D.pop()            // Returns 4.  The stacks are now:   1  3 
                                                        ﹈ ﹈   
D.pop()            // Returns 3.  The stacks are now:   1 
                                                        ﹈   
D.pop()            // Returns 1.  There are no stacks.
D.pop()            // Returns -1.  There are still no stacks.

Constraints:

1 <= capacity <= 20000
1 <= val <= 20000
0 <= index <= 100000
At most 200000 calls will be made to push, pop, and popAtStack.

我们把无限数量 ∞ 的栈排成一行，按从左到右的次序从 0 开始编号。每个栈的的最大容量 capacity 都相同。

实现一个叫「餐盘」的类 DinnerPlates：

DinnerPlates(int capacity) - 给出栈的最大容量 capacity。
void push(int val) - 将给出的正整数 val 推入从左往右第一个没有满的栈。
int pop() - 返回从右往左第一个非空栈顶部的值，并将其从栈中删除；如果所有的栈都是空的，请返回 -1。
int popAtStack(int index) - 返回编号 index 的栈顶部的值，并将其从栈中删除；如果编号 index 的栈是空的，请返回 -1。

示例：

输入： 
["DinnerPlates","push","push","push","push","push","popAtStack","push","push","popAtStack","popAtStack","pop","pop","pop","pop","pop"]
[[2],[1],[2],[3],[4],[5],[0],[20],[21],[0],[2],[],[],[],[],[]]
输出：
[null,null,null,null,null,null,2,null,null,20,21,5,4,3,1,-1]

解释：
DinnerPlates D = DinnerPlates(2);  // 初始化，栈最大容量 capacity = 2
D.push(1);
D.push(2);
D.push(3);
D.push(4);
D.push(5);         // 栈的现状为：    2  4
                                    1  3  5
                                    ﹈ ﹈ ﹈
D.popAtStack(0);   // 返回 2。栈的现状为：      4
                                          1  3  5
                                          ﹈ ﹈ ﹈
D.push(20);        // 栈的现状为：  20  4
                                   1  3  5
                                   ﹈ ﹈ ﹈
D.push(21);        // 栈的现状为：  20  4 21
                                   1  3  5
                                   ﹈ ﹈ ﹈
D.popAtStack(0);   // 返回 20。栈的现状为：       4 21
                                            1  3  5
                                            ﹈ ﹈ ﹈
D.popAtStack(2);   // 返回 21。栈的现状为：       4
                                            1  3  5
                                            ﹈ ﹈ ﹈ 
D.pop()            // 返回 5。栈的现状为：        4
                                            1  3 
                                            ﹈ ﹈  
D.pop()            // 返回 4。栈的现状为：    1  3 
                                           ﹈ ﹈   
D.pop()            // 返回 3。栈的现状为：    1 
                                           ﹈   
D.pop()            // 返回 1。现在没有栈。
D.pop()            // 返回 -1。仍然没有栈。

提示：

1 <= capacity <= 20000
1 <= val <= 20000
0 <= index <= 100000
最多会对 push，pop，和 popAtStack 进行 200000 次调用。

Runtime: 2024 ms

Memory Usage: 45 MB

 1 class DinnerPlates {
 2     var map:[Int:[Int]] = [Int:[Int]]()
 3     var cap:Int = 0
 4     var curr:Int = 0
 5     var last:Int = 0
 6     var count:Int = 0
 7 
 8     init(_ capacity: Int) {
 9         self.cap = capacity
10         map[curr] = [Int]()        
11     }
12     
13     func push(_ val: Int) {
14         while(map[curr] != nil  && map[curr,default:[Int]()].count == cap)
15         {
16             curr += 1
17         }
18         map[curr,default:[Int]()].append(val)
19         last = max(last, curr)
20         count += 1
21         
22     }
23     
24     func pop() -> Int {
25         if count == 0 {return -1}
26         while(last>=0 && map[last,default:[Int]()].isEmpty)
27         {
28             last -= 1
29         }
30         count -= 1
31         curr = min(curr, last)
32         return map[last,default:[Int]()].removeLast()
33     }
34     
35     func popAtStack(_ index: Int) -> Int {
36         if(map[index] == nil || map[index,default:[Int]()].isEmpty)
37         {
38             return -1
39         }
40         count -= 1
41         curr = min(curr, index)
42         return map[index,default:[Int]()].removeLast()
43     }
44 }
45 
46 /**
47  * Your DinnerPlates object will be instantiated and called as such:
48  * let obj = DinnerPlates(capacity)
49  * obj.push(val)
50  * let ret_2: Int = obj.pop()
51  * let ret_3: Int = obj.popAtStack(index)
52  */

[Swift]LeetCode1172. 餐盘栈 | Dinner Plate Stacks

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