opt页面置换算法实现c

以下是一个简单的 OPT 页面置换算法实现的 C 代码：

#include <stdio.h>

#define MAX_FRAMES 100

int main() {
    int num_frames, num_pages, frames[MAX_FRAMES], pages[MAX_FRAMES], page_faults = 0;
    printf("Enter the number of frames: ");
    scanf("%d", &num_frames);
    printf("Enter the number of pages: ");
    scanf("%d", &num_pages);
    printf("Enter the reference string: ");
    for (int i = 0; i < num_pages; i++) {
        scanf("%d", &pages[i]);
    }
    for (int i = 0; i < num_frames; i++) {
        frames[i] = -1; // Initialize all frames to -1
    }
    for (int i = 0; i < num_pages; i++) {
        int page_found = 0;
        for (int j = 0; j < num_frames; j++) {
            if (frames[j] == pages[i]) {
                page_found = 1; // Page is already in a frame
                break;
            }
        }
        if (!page_found) { // Page fault occurred
            int furthest_page = -1, furthest_index = -1;
            for (int j = 0; j < num_frames; j++) {
                int page_used = 0;
                for (int k = i + 1; k < num_pages; k++) {
                    if (frames[j] == pages[k]) {
                        page_used = 1; // Page will be used in future
                        if (k > furthest_index) {
                            furthest_index = k;
                            furthest_page = j;
                        }
                        break;
                    }
                }
                if (!page_used) { // Page will not be used in future
                    furthest_page = j;
                    break;
                }
            }
            frames[furthest_page] = pages[i]; // Replace the furthest page with current page
            page_faults++;
        }
    }
    printf("Total number of page faults: %d\n", page_faults);
    return 0;
}

该代码首先读取输入，包括帧数、页面数和引用串。然后，它初始化所有帧为 -1，表示它们都是空的。接下来，对于每个页面，它检查它是否在任何一个帧中。如果页面已经在一个帧中，它将跳过它。否则，它将查找哪个帧将在未来最远的时间使用，并将该帧替换为当前页面。如果没有帧将在未来使用，则选择第一个帧进行替换。最后，它输出页面错误的数量。