最佳适应算法
从全部空闲区中找出能满足作业要求的，且大小最小的空闲分区，这种方法能使碎片尽量小。
问题描述
- Given five memory partitions of 100 KB, 500 KB, 200 KB, 300 KB, and 600 KB (in order), how would each of the first-fit, best-fit, and worst-fit algorithms place processes of 212 KB, 417 KB, 112 KB, and 426 KB (in order)? Which algorithm makes the most efficient use of memory?
问题解决
为212k分配空间：
找到第一个跟212k大小最接近的空闲区找到第四个空闲区300>212k，剩余88k空闲区为417k分配空间：
找到第一个跟417k大小最接近的空闲区找到第二个空闲区500>417，剩余83k空闲区为112k分配空间：
找到第一个跟112k大小最接近的空闲区找到第三个空闲区200>112k，剩余88k空闲区为426k分配空间：
找到第一个跟426大小最接近的空闲区找到第五个空闲区600k>426，剩余74k空闲区
code
#include<stdio.h>
#include<stdlib.h>#define N 5
#define M 5int buf[N]={100,500,200,300,600};
int need_dis[M]={212,417,112,426,200};
typedef struct LNode *List;struct LNode{int order;int buffer;LNode *next;
};List list_init(){List head,p,m;int i;for(i=0;i<N;i++){if(i==0){m=(LNode*)malloc(sizeof(struct LNode));if(!m){printf("Error:memory!\n");exit(0);}m->order=i;m->buffer=buf[i];m->next=NULL;head=p=m;}else{m=(LNode*)malloc(sizeof(struct LNode));if(!m){printf("Error:memory wrong\n");exit(0);}m->order=i;m->buffer=buf[i];m->next=NULL;p->next=m;p=p->next;}}return head;
}void best_fit(List head){int i,j,k;int min;int order;List p;for(i=0;i<M;i++){min=-1;order=-1;p=head;while(p){if(p->buffer>=need_dis[i]){if(min<0){min=p->buffer-need_dis[i];order=p->order;}else{if(min>p->buffer-need_dis[i]){min=p->buffer-need_dis[i];order=p->order;}}}p=p->next;} if(order==-1){printf("\n");printf("分配完成%d个\n",i);printf("第%d个进程失败\n",i+1);printf("\n");break; }else{p=head;while(p){if(p->order==order)p->buffer-=need_dis[i];p=p->next;}}}
}void print(List p){while(p){printf("%d:%d\n",p->order,p->buffer);p=p->next;}
}int main(){List p;p=list_init();printf("分配内存前\n"); print(p);best_fit(p);printf("分配内存后\n");print(p);return 0;
} 
)
