Java语言程序设计编程题programming exercises答案第7章.docx
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Java语言程序设计编程题programmingexercises答案第7章
7.1importjava.util.Scanner;
publicclassExercise01{
publicstaticvoidmain（String[]args）{
Scannerinput=newScanner（System.in）;
System.out.println（"Entera4-by-4matrixrowbyrow:
"）;
int[][]matrix=newint[4][4];
for（inti=0;i<4;i++）{
for（intj=0;j<4;j++）{
matrix[i][j]=input.nextInt（）;
}
}
System.out.println（"Sumofthematrixis"+sumMatrix（matrix））;
}
publicstaticintsumMatrix（int[][]m）{
intsum=0;
for（inti=0;ifor（intj=0;jsum+=m[i][j];
}
}
returnsum;
}
}
7.2importjava.util.Scanner;
publicclassExercise02{
publicstaticvoidmain（String[]args）{
Scannerinput=newScanner（System.in）;
System.out.println（"Entera4-by-4matrixrowbyrow:
"）;
int[][]matrix=newint[4][4];
for（inti=0;ifor（intj=0;jmatrix[i][j]=input.nextInt（）;
}
}
System.out.println（"Sumoftheelementsinthemajordiagonalis"+sumMajorDiagonal（matrix））;
}
publicstaticintsumMajorDiagonal（int[][]m）{
intsum=0;
for（inti=0,j=0;isum+=m[i][j];
returnsum;
}
}
7.3publicclassExercise03{
publicstaticvoidmain（String[]args）{
//Student'sanswerstothequestions
char[][]answers={
{'A','B','A','C','C','D','E','E','A','D'},
{'D','B','A','B','C','A','E','E','A','D'},
{'E','D','D','A','C','B','E','E','A','D'},
{'C','B','A','E','D','C','E','E','A','D'},
{'A','B','D','C','C','D','E','E','A','D'},
{'B','B','E','C','C','D','E','E','A','D'},
{'B','B','A','C','C','D','E','E','A','D'},
{'E','B','E','C','C','D','E','E','A','D'}
};
//Keytothequestions
char[]keys={'D','B','D','C','C','D','A','E','A','D'};
int[][]countOfCorrect=newint[answers.length][2];
//Grandallanswers
for（inti=0;i//Gradeonestudent
intcorrectCount=0;
for（intj=0;jif（answers[i][j]==keys[j]）
correctCount++;
}
countOfCorrect[i][1]=correctCount;
countOfCorrect[i][0]=i;
}
for（inti=0;iintcurrentStudent=countOfCorrect[i][0];
intmin=countOfCorrect[i][1];
intminIndex=i;
for（intj=i+1;jif（countOfCorrect[j][1]currentStudent=countOfCorrect[j][0];
min=countOfCorrect[j][1];
minIndex=j;
}
}
if（minIndex!
=i）{
countOfCorrect[minIndex][0]=countOfCorrect[i][0];
countOfCorrect[minIndex][1]=countOfCorrect[i][1];
countOfCorrect[i][0]=currentStudent;
countOfCorrect[i][1]=min;
}
}
for（intj=0;jSystem.out.println（"Student"+countOfCorrect[j][0]+"'scorrectcountis"+countOfCorrect[j][1]）;
}
}
7.4publicclassExercise04{
publicstaticvoidmain（String[]args）{
int[][]workHours={
{2,4,3,4,5,8,8},
{7,3,4,3,3,4,4},
{9,3,4,7,3,4,1},
{3,5,3,4,6,3,8},
{3,4,4,6,3,4,4},
{3,7,4,8,3,8,4},
{6,3,5,9,2,7,9}
};
int[][]totalWorkHours=newint[workHours.length][2];
for（inti=0;iintsum=0;
for（intj=0;jsum+=workHours[i][j];
}
totalWorkHours[i][0]=i;
totalWorkHours[i][1]=sum;
}
int[][]sortTotalWorkHours=sortArray（totalWorkHours）;
for（intj=0;jSystem.out.println（"Employee"+sortTotalWorkHours[j][0]+"'stotalworkhoursis"+sortTotalWorkHours[j][1]）;
}
publicstaticint[][]sortArray（int[][]array）{
for（inti=0;iintcurrentEmployee=array[i][0];
intcurrentMaxWorkHours=array[i][1];
intcurrentMaxIndex=i;
for（intj=i+1;jif（array[j][1]>currentMaxWorkHours）{
currentEmployee=array[j][0];
currentMaxWorkHours=array[j][1];
currentMaxIndex=j;
}
}
if（currentMaxIndex!
=i）{
array[currentMaxIndex][0]=array[i][0];
array[currentMaxIndex][1]=array[i][1];
array[i][0]=currentEmployee;
array[i][1]=currentMaxWorkHours;
}
}
returnarray;
}
}
7.5importjava.util.Scanner;
publicclassExercise05{
publicstaticvoidmain（String[]args）{
Scannerinput=newScanner（System.in）;
System.out.println（"Entera4-by-4matrix1:
"）;
int[][]matrix1=newint[4][4];
int[][]matrix2=newint[4][4];
for（inti=0;ifor（intj=0;jmatrix1[i][j]=input.nextInt（）;
}
System.out.println（"Entera4-by-4matrix2:
"）;
for（inti=0;ifor（intj=0;jmatrix2[i][j]=input.nextInt（）;
}
int[][]sumOfMatrix=addMatrix（matrix1,matrix2）;
printMatrix（matrix1,matrix2,sumOfMatrix）;
}
publicstaticint[][]addMatrix（int[][]a,int[][]b）{
int[][]sum=newint[a.length][a[0].length];
for（inti=0;ifor（intj=0;jsum[i][j]=a[i][j]+b[i][j];
}
returnsum;
}
publicstaticvoidprintMatrix（int[][]matrix1,int[][]matrix2,int[][]sumOfMatrix）{
for（inti=0;ifor（intj=0;jSystem.out.print（（matrix1[i][j]<10?
"":
""）+matrix1[i][j]+""）;
}
if（i!
=Math.ceil（matrix1.length/2））
System.out.print（""）;
else
System.out.print（"+"）;
for（intj=0;jSystem.out.print（（matrix2[i][j]<10?
"":
""）+matrix2[i][j]+""）;
}
if（i!
=Math.ceil（matrix1.length/2））
System.out.print（""）;
else
System.out.print（"="）;
for（intj=0;jSystem.out.print（（sumOfMatrix[i][j]<10?
"":
""）+sumOfMatrix[i][j]+""）;
}
System.out.println（）;
}
}
}
7.6importjava.util.Scanner;
publicclassExercise06{
publicstaticvoidmain（String[]args）{
Scannerinput=newScanner（System.in）;
double[][]matrix1=newdouble[3][3];
double[][]matrix2=newdouble[3][3];
System.out.println（"Entera3-by-3matrix1:
"）;
for（inti=0;ifor（intj=0;jmatrix1[i][j]=input.nextDouble（）;
}
System.out.println（"Entera3-by-3matrix2:
"）;
for（inti=0;ifor（intj=0;jmatrix2[i][j]=input.nextDouble（）;
}
double[][]multiplyMatrix=multiplyMatrix（matrix1,matrix2）;
for（inti=0;ifor（intj=0;jSystem.out.print（matrix1[i][j]+""）;
}
if（i!
=Math.ceil（matrix1.length/2））
System.out.print（""）;
else
System.out.print（"*"）;
for（intj=0;jSystem.out.print（matrix2[i][j]+""）;
}
if（i!
=Math.ceil（matrix1.length/2））
System.out.print（""）;
else
System.out.print（"="）;
for（intj=0;jSystem.out.print（（int）（multiplyMatrix[i][j]*10）/10.0+""）;
}
System.out.println（）;
}
}
publicstaticdouble[][]multiplyMatrix（double[][]a,double[][]b）{
double[][]multiply=newdouble[a.length][a[0].length];
for（inti=0;ifor（intj=0;jfor（intm=0;mmultiply[i][j]+=a[i][m]*b[m][j];
}
}
returnmultiply;
}
}
7.7publicclassExercise07{
publicstaticvoidmain（String[]args）{
double[][]points={{-1,0,3},{-1,-1,-1},{4,1,1},{2,0.5,9},{3.5,2,-1},{3,1.5,3},{-1.5,4,2},{5.5,4,-0.5}};
//p1andp2aretheindicesinthepointsarray
intp1=0,p2=1;//Initialtwopoints
doubleshortestDistance=distance（points[p1][0],points[p1][1],points[p1][2],
points[p2][0],points[p2][1],points[p2][2]）;//InitializeshortestDistance
//Computedistanceforeverytwopoints
for（inti=0;ifor（intj=i+1;jdoubledistance=distance（points[i][0],points[i][1],points[i][2],
points[j][0],points[j][1],points[j][2]）;//Finddistance
if（distancep1=i;//Updatep1
p2=j;//Updatep2
shortestDistance=distance;//UpdateshortestDistance
}
}
}
//Displayresult
System.out.println（"Theclosesttwopointsare"+"（"+points[p1][0]+","+points[p1][1]+points[p1][2]+"）and（"+
points[p2][0]+","+points[p2][1]+points[p2][2]+"）"）;
}
publicstaticdoubledistance（doublex1,doubley1,doublez1,doublex2,doubley2,doublez2）{
returnMath.sqrt（（x2-x1）*（x2-x1）+（y2-y1）*（y2-y1）+（z2-z1）*（z2-z1））;
}
}
7.8importjava.util.Scanner;
publicclassExercise08{
publicstaticvoidmain（String[]args）{
double[][]points={{-1,3},{-1,-1},{1,1},{0,0.5},
{2,0.5},{2,-1},{3,3},{4,2},{4,-0.5}};
//p1andp2aretheindicesinthepointsarray
intp1=0,p2=1;//Initialtwopoints
doubleshortestDistance=distance（points[p1][0],points[p1][1],
points[p2][0],points[p2][1]）;//InitializeshortestDistance
int[][]indices=newint[points.length][2];
intk=0;
ind
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