Follow your Heart, Fly your Foot

package cn.yodes.OS.Algorithm;
public class FIFO {
	
public void start(int []page , int []block){
	int index_old = 0 , pre = 0 , current = 0;
	boolean flag = false;
	
	for(int i = 0; i < block.length; i++){
		block[i] = -1;
	}
	for(int i = 0; i < page.length; i++){
		flag = false;
		for(int j : block){
			if(page[i] == j){
				flag = true;	
				break;
			}
		}
		if(!flag){
			if(pre < block.length){
				current = pre++;
			}else{
				current = index_old++ % block.length;
			}
			block[current] = page[i];
		}
		for(int k : block){
			System.out.print(k + "\t");
		}
		System.out.println();
	}
}
	
public static void main(String[] args) {
	FIFO test = new FIFO();
	int sum_page = 20;
	int []page = new int[sum_page];
	
	int sum_block = 5;
	int[] block = new int[sum_block];
	for(int i = 0; i < page.length; i++){
		page[i] = (int) (Math.random()*10);
		System.out.print(page[i] + "  ");
	}
	System.out.println();
//		test.addEle(page, block);
	test.start(page, block);
}
}

package cn.yodes.OS.Algorithm;
public class LRU {
	 
 public void start(int[] page , int[] block){
	 int[] temp = new int[block.length];
	 int current = 0;
	 boolean flag = false;
	 for(int i = 0; i < temp.length; i++){
		 temp[i] = i;
		 block[i] = -1;
	 }
	 
	 for(int i = 0; i < page.length; i++){
		 flag = false;
		 for(int j = 0; j < block.length; j++){
			 if(page[i] == block[j]){ flag = true;  current = j; 	break;}
		 }
		 
		 if(!flag){
			 for(int j = 0; j < temp.length; j++){
				 if( temp[j] == 0 )	{	current = j; 	break;}
			 }
			 block[current] = page[i];
		 
			 for(int j = 0; j < temp.length; j++){
				 if(temp[j] > temp[current])	{ temp[j] = (temp[j] - 1) % 4;}
			 }
			 temp[current] = temp.length - 1;
		 }
		 for(int k : block)
			 System.out.print(k + "\t");
		 System.out.println();
	 }
 }
 
 public static void main(String[] args) {
	LRU test = new LRU();
	int sum_page = 20;
	int []page = new int[sum_page];
	
	int sum_block = 5;
	int[] block = new int[sum_block];
	for(int i = 0; i < page.length; i++){
		page[i] = (int) (Math.random()*10);
		System.out.print(page[i] + "  ");
	}
	System.out.println();
	
	test.start(page, block);
}
}

package cn.yodes.OS.Algorithm;

public class Optimal {
	
public void start(int[] page , int[] block){
	int[] temp = new int[block.length];
	int current = 0;
	boolean flag = false;
	for(int i = 0; i < block.length; i++){
		block[i] = -1;
	}
	for(int i = 0; i < page.length; i++){
		flag = false;
		for(int j : block){	
			if(j == page[i])	{	flag = true;			}
		}
		if(!flag){
			if(current < block.length){
				block[current++] = page[i];
			}else{
				temp = new int[block.length];
				for(int k = 0; k < temp.length; k++)
					for(int j = i; j < page.length ; j++)
						if(page[j] != block[k])	{	
							temp[k]++;
						} else{
							break;
						}
				current = getIndexOfMaxVal(temp);
//					System.out.print("m:");
//					for(int m : temp){
//						System.out.print(m + "\t");
//					}
				block[current] = page[i];
			}
		}
//			for(int l : block){
//				System.out.print(l + "\t");
//			}
		System.out.println();
	}
}

	public int getIndexOfMaxVal(int[] data){
		int maxVal = data[0];
		int maxInd = 0;
		for(int i = 1; i < data.length; i++){
			if(data[i] > maxVal){
				maxVal = data[i];
				maxInd = i;
			}
		}
	//		System.out.println("maxInd=" + maxInd);
		return maxInd;
	}
	public static void main(String[] args) {
		Optimal Test = new Optimal();
		int sum_page = 20;
		int []page = new int[sum_page];
		
		int sum_block = 5;
		int[] block = new int[sum_block];
		for(int i = 0; i < page.length; i++){
			page[i] = (int) (Math.random()*10);
			System.out.print(page[i] + "  ");
		}
		System.out.println();
		Test.start(page, block);
	}
}