最坏适应算法C++的源代码

以下是最坏适应算法的简单C++实现：

#include <iostream>
#include <cstdlib> // for malloc() and free()

using namespace std;

// define a struct to store information about a memory block
struct MemoryBlock {
    int size;
    bool free;
};

// define global variables
const int MAX_MEMORY = 1024; // maximum memory size
void* memory = malloc(MAX_MEMORY); // pointer to the memory block
MemoryBlock* memoryBlock = (MemoryBlock*)memory; // first memory block

// function to allocate memory using worst-fit algorithm
void* allocateMemory(int size) {
    MemoryBlock* current = memoryBlock;
    MemoryBlock* worstBlock = NULL;

    // find the worst-fit memory block
    while (current < (MemoryBlock*)((char*)memory + MAX_MEMORY)) {
        if (current->free && current->size >= size) {
            if (worstBlock == NULL || current->size > worstBlock->size) {
                worstBlock = current;
            }
        }
        current = (MemoryBlock*)((char*)current + current->size + sizeof(MemoryBlock));
    }

    // allocate memory in the worst-fit memory block
    if (worstBlock != NULL) {
        if (worstBlock->size >= size + sizeof(MemoryBlock) + 1) {
            // split the memory block into two blocks
            MemoryBlock* newBlock = (MemoryBlock*)((char*)worstBlock + sizeof(MemoryBlock) + size);
            newBlock->size = worstBlock->size - size - sizeof(MemoryBlock);
            newBlock->free = true;
            worstBlock->size = size;
            worstBlock->free = false;
            return (void*)((char*)worstBlock + sizeof(MemoryBlock));
        }
        else {
            worstBlock->free = false;
            return (void*)((char*)worstBlock + sizeof(MemoryBlock));
        }
    }

    // no available memory block
    return NULL;
}

// function to free memory
void freeMemory(void* ptr) {
    if (ptr != NULL) {
        MemoryBlock* block = (MemoryBlock*)((char*)ptr - sizeof(MemoryBlock));
        block->free = true;

        // merge adjacent free memory blocks
        MemoryBlock* current = memoryBlock;
        while (current < (MemoryBlock*)((char*)memory + MAX_MEMORY)) {
            if (current->free) {
                MemoryBlock* next = (MemoryBlock*)((char*)current + current->size + sizeof(MemoryBlock));
                while (next < (MemoryBlock*)((char*)memory + MAX_MEMORY) && next->free) {
                    current->size += next->size + sizeof(MemoryBlock);
                    next = (MemoryBlock*)((char*)current + current->size + sizeof(MemoryBlock));
                }
            }
            current = (MemoryBlock*)((char*)current + current->size + sizeof(MemoryBlock));
        }
    }
}

int main() {
    // allocate memory
    void* ptr1 = allocateMemory(100);
    void* ptr2 = allocateMemory(200);
    void* ptr3 = allocateMemory(300);

    // free memory
    freeMemory(ptr2);

    // allocate memory again
    void* ptr4 = allocateMemory(150);

    // print memory information
    MemoryBlock* current = memoryBlock;
    while (current < (MemoryBlock*)((char*)memory + MAX_MEMORY)) {
        cout << "Memory block " << current - memoryBlock << ": size=" << current->size << ", free=" << current->free << endl;
        current = (MemoryBlock*)((char*)current + current->size + sizeof(MemoryBlock));
    }

    // free memory
    freeMemory(ptr1);
    freeMemory(ptr3);
    freeMemory(ptr4);
    return 0;
}

在这个实现中，我们定义了一个`MemoryBlock`结构体来存储内存块的信息，包括大小和是否被使用。我们使用`malloc()`函数分配了一个指定大小的内存块，并将其存储在`memory`指针中。然后，我们将第一个内存块的信息存储在`memoryBlock`指针中。

`allocateMemory()`函数使用最坏适应算法来分配内存。它遍历整个内存块链表，查找最大的可用内存块，并将其分配给请求的大小。如果可用内存块大于请求的大小，我们将该内存块分割成两个块，一个用于请求的大小，另一个用于剩余的大小。如果没有可用的内存块，则返回`NULL`。

`freeMemory()`函数用于释放内存。它接受一个指向要释放的内存块的指针，并将该内存块标记为未使用。然后，它将相邻的空闲内存块合并为一个更大的块。

最后，我们在`main()`函数中演示了如何使用该实现来分配和释放内存，并打印了内存块的信息。