{ "data": { "question": { "questionId": "2587", "questionFrontendId": "2502", "categoryTitle": "Algorithms", "boundTopicId": 2012709, "title": "Design Memory Allocator", "titleSlug": "design-memory-allocator", "content": "
You are given an integer n
representing the size of a 0-indexed memory array. All memory units are initially free.
You have a memory allocator with the following functionalities:
\n\nsize
consecutive free memory units and assign it the id mID
.mID
.Note that:
\n\nmID
.mID
, even if they were allocated in different blocks.Implement the Allocator
class:
Allocator(int n)
Initializes an Allocator
object with a memory array of size n
.int allocate(int size, int mID)
Find the leftmost block of size
consecutive free memory units and allocate it with the id mID
. Return the block's first index. If such a block does not exist, return -1
.int free(int mID)
Free all memory units with the id mID
. Return the number of memory units you have freed.\n
Example 1:
\n\n\nInput\n["Allocator", "allocate", "allocate", "allocate", "free", "allocate", "allocate", "allocate", "free", "allocate", "free"]\n[[10], [1, 1], [1, 2], [1, 3], [2], [3, 4], [1, 1], [1, 1], [1], [10, 2], [7]]\nOutput\n[null, 0, 1, 2, 1, 3, 1, 6, 3, -1, 0]\n\nExplanation\nAllocator loc = new Allocator(10); // Initialize a memory array of size 10. All memory units are initially free.\nloc.allocate(1, 1); // The leftmost block's first index is 0. The memory array becomes [1,_,_,_,_,_,_,_,_,_]. We return 0.\nloc.allocate(1, 2); // The leftmost block's first index is 1. The memory array becomes [1,2,_,_,_,_,_,_,_,_]. We return 1.\nloc.allocate(1, 3); // The leftmost block's first index is 2. The memory array becomes [1,2,3,_,_,_,_,_,_,_]. We return 2.\nloc.free(2); // Free all memory units with mID 2. The memory array becomes [1,_, 3,_,_,_,_,_,_,_]. We return 1 since there is only 1 unit with mID 2.\nloc.allocate(3, 4); // The leftmost block's first index is 3. The memory array becomes [1,_,3,4,4,4,_,_,_,_]. We return 3.\nloc.allocate(1, 1); // The leftmost block's first index is 1. The memory array becomes [1,1,3,4,4,4,_,_,_,_]. We return 1.\nloc.allocate(1, 1); // The leftmost block's first index is 6. The memory array becomes [1,1,3,4,4,4,1,_,_,_]. We return 6.\nloc.free(1); // Free all memory units with mID 1. The memory array becomes [_,_,3,4,4,4,_,_,_,_]. We return 3 since there are 3 units with mID 1.\nloc.allocate(10, 2); // We can not find any free block with 10 consecutive free memory units, so we return -1.\nloc.free(7); // Free all memory units with mID 7. The memory array remains the same since there is no memory unit with mID 7. We return 0.\n\n\n
\n
Constraints:
\n\n1 <= n, size, mID <= 1000
1000
calls will be made to allocate
and free
.给你一个整数 n
,表示下标从 0 开始的内存数组的大小。所有内存单元开始都是空闲的。
请你设计一个具备以下功能的内存分配器:
\n\nsize
的连续空闲内存单元并赋 id mID
。mID
对应的所有内存单元。注意:
\n\nmID
。mID
对应的所有内存单元,即便这些内存单元被分配在不同的块中。实现 Allocator
类:
Allocator(int n)
使用一个大小为 n
的内存数组初始化 Allocator
对象。int allocate(int size, int mID)
找出大小为 size
个连续空闲内存单元且位于 最左侧 的块,分配并赋 id mID
。返回块的第一个下标。如果不存在这样的块,返回 -1
。int free(int mID)
释放 id mID
对应的所有内存单元。返回释放的内存单元数目。\n\n
示例:
\n\n输入\n[\"Allocator\", \"allocate\", \"allocate\", \"allocate\", \"free\", \"allocate\", \"allocate\", \"allocate\", \"free\", \"allocate\", \"free\"]\n[[10], [1, 1], [1, 2], [1, 3], [2], [3, 4], [1, 1], [1, 1], [1], [10, 2], [7]]\n输出\n[null, 0, 1, 2, 1, 3, 1, 6, 3, -1, 0]\n\n解释\nAllocator loc = new Allocator(10); // 初始化一个大小为 10 的内存数组,所有内存单元都是空闲的。\nloc.allocate(1, 1); // 最左侧的块的第一个下标是 0 。内存数组变为 [1, , , , , , , , , ]。返回 0 。\nloc.allocate(1, 2); // 最左侧的块的第一个下标是 1 。内存数组变为 [1,2, , , , , , , , ]。返回 1 。\nloc.allocate(1, 3); // 最左侧的块的第一个下标是 2 。内存数组变为 [1,2,3, , , , , , , ]。返回 2 。\nloc.free(2); // 释放 mID 为 2 的所有内存单元。内存数组变为 [1, ,3, , , , , , , ] 。返回 1 ,因为只有 1 个 mID 为 2 的内存单元。\nloc.allocate(3, 4); // 最左侧的块的第一个下标是 3 。内存数组变为 [1, ,3,4,4,4, , , , ]。返回 3 。\nloc.allocate(1, 1); // 最左侧的块的第一个下标是 1 。内存数组变为 [1,1,3,4,4,4, , , , ]。返回 1 。\nloc.allocate(1, 1); // 最左侧的块的第一个下标是 6 。内存数组变为 [1,1,3,4,4,4,1, , , ]。返回 6 。\nloc.free(1); // 释放 mID 为 1 的所有内存单元。内存数组变为 [ , ,3,4,4,4, , , , ] 。返回 3 ,因为有 3 个 mID 为 1 的内存单元。\nloc.allocate(10, 2); // 无法找出长度为 10 个连续空闲内存单元的空闲块,所有返回 -1 。\nloc.free(7); // 释放 mID 为 7 的所有内存单元。内存数组保持原状,因为不存在 mID 为 7 的内存单元。返回 0 。\n\n\n
\n\n
提示:
\n\n1 <= n, size, mID <= 1000
allocate
和 free
方法 1000
次\\u7248\\u672c\\uff1a \\u7f16\\u8bd1\\u65f6\\uff0c\\u5c06\\u4f1a\\u91c7\\u7528 \\u4e3a\\u4e86\\u4f7f\\u7528\\u65b9\\u4fbf\\uff0c\\u5927\\u90e8\\u5206\\u6807\\u51c6\\u5e93\\u7684\\u5934\\u6587\\u4ef6\\u5df2\\u7ecf\\u88ab\\u81ea\\u52a8\\u5bfc\\u5165\\u3002<\\/p>\"],\"java\":[\"Java\",\" \\u7248\\u672c\\uff1a \\u4e3a\\u4e86\\u65b9\\u4fbf\\u8d77\\u89c1\\uff0c\\u5927\\u90e8\\u5206\\u6807\\u51c6\\u5e93\\u7684\\u5934\\u6587\\u4ef6\\u5df2\\u88ab\\u5bfc\\u5165\\u3002<\\/p>\\r\\n\\r\\n \\u5305\\u542b Pair \\u7c7b: https:\\/\\/docs.oracle.com\\/javase\\/8\\/javafx\\/api\\/javafx\\/util\\/Pair.html <\\/p>\"],\"python\":[\"Python\",\" \\u7248\\u672c\\uff1a \\u4e3a\\u4e86\\u65b9\\u4fbf\\u8d77\\u89c1\\uff0c\\u5927\\u90e8\\u5206\\u5e38\\u7528\\u5e93\\u5df2\\u7ecf\\u88ab\\u81ea\\u52a8 \\u5bfc\\u5165\\uff0c\\u5982\\uff1aarray<\\/a>, bisect<\\/a>, 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rust 1.58.1<\\/code><\\/p>\\r\\n\\r\\n
PHP 8.1<\\/code>.<\\/p>\\r\\n\\r\\n