最坏适应算法c++的源代码
时间: 2023-10-12 10:21:11 浏览: 49
以下是最坏适应算法的简单C++实现:
```c++
#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。