先进先出置换算法（FIFO）

算法原理

#include<iostream>
#include<cstdio>
using namespace std;

bool find(int number);
void print(int * array, int length);
int page[25] = {0, 7, 0, 1, 2, 0, 3, 0, 4, 2, 3, 0, 3,
                  2, 1, 2, 0, 1, 7, 0, 1};//第一个元素不算 

const int memory_len = 4, page_len = 20;//内存大小, 页的大小
int memory[memory_len+1];

int main() {
  int memory_pos = 1, page_pos = memory_len+1;//内存位置和页的位置 
  printf("页面置换过程：\n");

  for (int i = 1; i <= memory_len; i++) {
    if (find(page[i])) memory[i] = page[i];
    print(memory, i);
  }

  while (page_pos <= page_len) {
    if (find(page[page_pos])) {

      if (memory_pos > memory_len) memory_pos = 1;

      memory[memory_pos++] = page[page_pos];
      page_pos++;
      print(memory, memory_len);

    }else {
      page_pos++;
    }
  }

    return 0;
}

void print(int * array, int length) {
  for (int i = 1; i <= length; i++) {
    printf("%d ", array[i]);
  }
  printf("\n");
}

bool find(int number) {
  for (int i = 1; i <= memory_len; i++) {
    if (memory[i] == number) return false;
  }
  return true;
}