diff --git a/Codes/p11/p11.cpp b/Codes/p11/p11.cpp
new file mode 100644
index 0000000..3744ccc
--- /dev/null
+++ b/Codes/p11/p11.cpp
@@ -0,0 +1,155 @@
+#include<iostream.h>
+#include<math.h>
+#include <string>
+using  std::string;
+
+
+double temp[4][5];
+double temp1[5][6];
+
+
+double compEntropy(double a[][5])           //ěŘ
+{
+  double sum = 0;
+  int n = sizeof(a) / sizeof(double);
+  for(int i = 0;i < 4;i++)
+    for(int j = 0;j < 5;j++)
+    sum+=-a[i][j]*(log(a[i][j])/log(2));
+  return sum;
+}
+
+void output(double a[][5],int nRow,int nCol)     //matrix output
+{
+  for(int i = 0;i < nRow;i++)
+  {
+    for(int j = 0;j < nCol;j++)
+      cout<<a[i][j]<<"\t";
+    cout<<endl;
+  }
+}
+
+
+double max(double q[][5],int &m,int &n)      //print maximum valie and index
+{
+	double maxv = 0;
+	for(int i = 0;i < 4;i++)
+      for(int j = 0;j < 5;j++)
+	  {
+	 	  if(maxv < q[i][j])
+		  { 
+			maxv = q[i][j];
+			m = i;
+			n = j;
+		  }
+
+	  }
+	return maxv;
+}
+
+void move(double q[][5],int nRow,int nCol,int u[][2],int k)     //move function
+{
+  int m,n;
+  for(int i = 1;i < (nRow + 1);i++)
+    for(int j = 1;j < (nCol + 1);j++)
+	{	
+		if((i-1-u[k][0]) < 0)                        
+			m = (i-1-u[k][0]) + 8;
+		else
+			m = abs(i-1-u[k][0]);
+
+		if((j-1-u[k][1]) < 0)
+			n = (j-1-u[k][1]) + 10;
+		else
+			n = abs(j-1-u[k][1]);
+       temp1[i][j] = 0.8*q[m % 4 ][n % 5 ]+0.2* q[i-1][j-1];  //mod 
+		
+	}
+  for(int ii = 0;ii < 4;ii++)
+    for(int j = 0 ;j < 5;j++)
+		temp[ii][j] = temp1[ii+1][j+1];
+
+		
+}
+
+void sense(double q[][5],string z,string world1[][5])     //sense function
+{
+  int hit;
+  for(int i = 0;i < 4;i++)
+    for(int j = 0;j < 5;j++)
+    {
+		if(z == world1[i][j])
+			hit = 1;
+		else 
+			hit = 0;
+	
+	temp[i][j] = q[i][j] *(hit * 0.7 + (1-hit) * (1 - 0.7)); 
+
+    }
+}
+
+
+
+void  main()
+{
+	string world[4][5] ={{"red", "green", "green", "red" , "red"},
+       					 {"red", "red", "green", "red",  "red"},
+       					 {"red", "red", "green", "green",  "red"},
+        				 {"red", "red", "red", "red",  "red"}};
+	int nRow = sizeof(world) / sizeof(world[0]);  
+	int nCol = sizeof(world[0]) / sizeof(world[0][0]);
+	int motions[][2] = {{0, 0}, {0, 1}, {1, 0}, {1, 0},{0, 1}};
+	int eCol = sizeof(motions) / sizeof(motions[0]);
+	double entropy[2][5];
+	double sum1 = 0;
+    string measurements[] = {"green", "green", "green" ,"green", "green"};
+    double p[4][5],p0[4][5];
+   	
+	int r_index = 0,c_index = 0;
+	double maxV;
+	for(int i = 0;i < nRow;i++)
+		for(int j = 0;j<nCol;j++)
+		p[i][j] = (double)1/(nRow*nCol);
+
+//	for(int ii=0;ii<2;ii++)
+//	  for(int j=0;j<eCol;j++)
+//		entropy[ii][j] = 0;
+
+	for(int k=0;k<eCol;k++)                 //The main loop
+	  {
+		move(p,nRow,nCol,motions,k);     	//Compute move
+		for(int i=0;i<nRow;i++)
+		  for(int j=0;j<nCol;j++)
+			{
+			  p[i][j] = temp[i][j];
+			  p0[i][j] = p[i][j];
+			}
+
+		sense(p,measurements[i], world);   //Compute sense
+		for(int ii=0;ii<nRow;ii++)         
+            for(int j=0;j<nCol;j++)
+				{
+					p[ii][j] = temp[ii][j];
+					sum1+= p[ii][j];
+				}
+	
+		for(int i1=0;i1<nRow;i1++)
+            for(int j=0;j<nCol;j++)
+				p[i1][j] = (double)p[i1][j]/sum1; 
+		sum1 = 0;
+       
+		entropy[0][k]=compEntropy(p0);
+		entropy[1][k]=compEntropy(p);
+
+
+		 cout<<"step"<<k<<"The probability before sensing:"<<endl;
+		 output(p0,nRow,nCol);
+		 cout<<"step"<<k<<"The probability after sensing:"<<endl;
+		 output(p,nRow,nCol);
+	}
+	maxV=max(p,r_index,c_index);
+	cout<<"The largest probability "<<maxV<<" occurs at cell"<<"["<<r_index<<"]["<<c_index<<"]"<<endl;
+	cout<<"The change of entropy:"<<endl;
+	output(entropy,2,5);
+
+
+}
\ No newline at end of file
diff --git a/Codes/p12/p12.cpp b/Codes/p12/p12.cpp
new file mode 100644
index 0000000..501bab1
--- /dev/null
+++ b/Codes/p12/p12.cpp
@@ -0,0 +1,26 @@
+#include<iostream.h>
+int main()
+{
+  double p[2],p1[2];
+  double pCan = 0.001;
+  double pNon = 0.999;       
+  char *z = "positive";   
+  //z = 'negative'; 
+  double pPosCan = 0.8;                          
+  double pPosNon = 0.1;
+ if("positive"==z)
+  {  
+    p[0] = pPosCan * pCan;
+    p[1] = pPosNon * pNon;
+  }
+ else
+  {
+    p[0] = (1-pPosCan) * pCan;
+    p[1] = (1-pPosNon) * pNon;
+  }
+    p1[0] = p[0] / (p[0]+p[1]);
+    p1[1] = p[1] / (p[0]+p[1]);
+    cout<<"The probability of having cancer given the positive test:\n"<<p1[0]<<endl<<"The probability of cancer free given positive the test:\n"<<p1[1]<<endl;
+
+
+}
diff --git a/Codes/p13/p13.cpp b/Codes/p13/p13.cpp
new file mode 100644
index 0000000..395ef77
--- /dev/null
+++ b/Codes/p13/p13.cpp
@@ -0,0 +1,30 @@
+#include<iostream.h>
+
+int ave(int a[],int n)
+{
+  int sum = 0;
+  for(int i=0;i<n;i++)
+	sum+=a[i];
+ 
+  return sum / n;
+}
+
+double var(int a[],int n)  
+{  
+    int sum = 0;  
+    int average = ave(a,n);
+    for(int i = 0;i<n;i++)  
+      sum+= (a[i]-average) * (a[i]-average);  
+    return sum / (n*1.0);  
+}
+
+int main(void)
+{
+  int n;
+  int x1[] = {7,38,4,23,18};
+  int x2[] = {17,19,18,17,19};
+  int x3[] = {18,18,18,18,18};
+  n = sizeof(x1) / sizeof(int);
+  cout<<ave(x1,n)<<endl<<var(x1,n)<<endl<<ave(x2,n)<<endl<<var(x2,n)<<endl<<ave(x3,n)<<endl<<var(x3,n)<<endl;
+  return 0;
+}