LRU页面置换算法

本文以序列长度20的{ 7,0,1,2,0,3,0,4,2,3,0,3,2,1,2,0,1,7,0,1};以及页面4；为例；

 #include <stdio.h>

 #define InitPysiBlocks 4
 #define MaxPages 20
 int PysicalBlocks[InitPysiBlocks] = { -,-,-,- };
 int PageSequence[MaxPages] = { ,,,,,,,,,,,,,,,,,,,};

 void LRU(int py[],int pg[])
 {
     int i,j,k,m,flag[MaxPages],temp[MaxPages][InitPysiBlocks];
     int max = ;
     char f[MaxPages];
     for(i = ; i < InitPysiBlocks; i++)
     {
         py[i] = pg[i];
         flag[i] = i;
         f[i] = '*';
         for(j = ; j < InitPysiBlocks; j++)
             temp[i][j] = py[j];
     }
     for(i = InitPysiBlocks; i < MaxPages; i++)
     {
         for(j = ,k = ; j < InitPysiBlocks; j++)
         {
             if(py[j] != pg[i])
                 k++;
             else
                 flag[j] = i;
         }
         if(k == InitPysiBlocks)
         {
             f[i] = '*';
             max = flag[] < flag[]?:;
             for(m = ; m < InitPysiBlocks; m++)
                 if(flag[m] < flag[max])
                     max = m;
             py[max] = pg[i];
             flag[max] = i;
             for(j = ; j < InitPysiBlocks; j++)
                 temp[i][j] = py[j];
         }
         else
         {
             f[i] = ' ';
             for(j = ; j < InitPysiBlocks; j++)
                 temp[i][j] = py[j];
         }
     }
     printf("输出结果为下表(-1代表为空,*代表有缺页)：\n");
     for(i = ; i < InitPysiBlocks; i++)
     {
         for(j = ; j < MaxPages; j++)
             printf("%3d",temp[j][i]);
         printf("\n");
     }
     for(i = ; i < MaxPages; i++)
         printf("%3c",f[i]);
     printf("\n");
 }

 void main()
 {
     LRU(PysicalBlocks,PageSequence);
 }

测试：