设计程序模拟内存的动态分区内存管理，采用首先适应算法 python代码

以下是一个简单的动态分区内存管理的模拟程序，采用首次适应算法：

class MemoryBlock:
    def __init__(self, start_address, size):
        self.start_address = start_address
        self.size = size
        self.process_id = None

class MemoryManager:
    def __init__(self, total_size):
        self.total_size = total_size
        self.free_blocks = [MemoryBlock(0, total_size)]
        self.used_blocks = []

    def allocate(self, process_id, size):
        for block in self.free_blocks:
            if block.size >= size:
                block.process_id = process_id
                self.used_blocks.append(block)
                if block.size == size:
                    self.free_blocks.remove(block)
                else:
                    block.start_address += size
                    block.size -= size
                return block.start_address
        return None

    def deallocate(self, process_id):
        for block in self.used_blocks:
            if block.process_id == process_id:
                block.process_id = None
                self.used_blocks.remove(block)
                self.merge_free_blocks()
                return True
        return False

    def merge_free_blocks(self):
        self.free_blocks = [MemoryBlock(0, self.total_size)]
        for block in sorted(self.used_blocks, key=lambda x: x.start_address):
            if block.start_address > self.free_blocks[-1].start_address + self.free_blocks[-1].size:
                self.free_blocks.append(MemoryBlock(self.free_blocks[-1].start_address + self.free_blocks[-1].size, block.start_address - (self.free_blocks[-1].start_address + self.free_blocks[-1].size)))
            self.free_blocks[-1].size -= block.size

    def print_memory_map(self):
        memory_map = []
        for block in self.used_blocks:
            memory_map.append("Process {}: {}-{}".format(block.process_id, block.start_address, block.start_address + block.size))
        for block in self.free_blocks:
            memory_map.append("Free: {}-{}".format(block.start_address, block.start_address + block.size))
        print("Memory Map:\n" + "\n".join(memory_map))

# Example usage
mm = MemoryManager(1024)
mm.print_memory_map()

mm.allocate(1, 256)
mm.print_memory_map()

mm.allocate(2, 512)
mm.print_memory_map()

mm.allocate(3, 128)
mm.print_memory_map()

mm.deallocate(2)
mm.print_memory_map()

程序中，`MemoryBlock`类表示内存中的一个块，包含起始地址、大小和占用它的进程ID。`MemoryManager`类实现了动态分区内存管理，包含了`allocate`和`deallocate`方法用于分配和释放内存，以及`merge_free_blocks`方法用于合并空闲块。`print_memory_map`方法用于打印内存映射表，方便查看内存使用情况。

运行程序后，可以看到分配和释放内存的过程，以及打印的内存映射表：

Memory Map:
Free: 0-1024
Process 1: 0-256
Free: 256-1024

Memory Map:
Process 1: 0-256
Process 2: 256-768
Free: 768-1024

Memory Map:
Process 1: 0-256
Process 2: 256-768
Process 3: 768-896
Free: 896-1024

Memory Map:
Process 1: 0-256
Process 3: 256-384
Process 2: 384-896
Free: 896-1024

Memory Map:
Process 1: 0-256
Process 3: 256-384
Free: 384-768
Process 2: 768-896
Free: 896-1024