Programming exercises for the 3rd and 4 chapters of Java language programming

3.1

 Public classTest { Public Static voidMain (string[] args) {System.out.println ("Enter A, B, C:"); Scanner input=NewScanner (system.in); DoubleA =input.nextdouble (); Doubleb =input.nextdouble (); Doublec =input.nextdouble (); DoubleDelta = b * b-4 * A *C; Doublet = Math.pow (Delta, 0.5); if(Delta > 0) {            DoubleX1 = (-B + t)/2; Doublex2 = (-b-t)/2; System.out.println ("The Roots is" + x1 + "+" +x2); } Else if(Delta = = 0) {System.out.println ("The root is" +-b/(2 *a)); } Else{System.out.println ("The equation has no real roots"); }    }}

3.2

 Public classTest { Public Static voidMain (string[] args) {System.out.println ("Enter An integer:"); Scanner input=NewScanner (system.in); intn =Input.nextint (); System.out.print ("is" + N + "an even number?"); if(n% 2 = = 0) System.out.println ("True"); ElseSystem.out.println ("False"); }}

3.3

 Public classTest { Public Static voidMain (string[] args) {System.out.print ("Enter A, B, C, D, E, F:"); Scanner input=NewScanner (system.in); DoubleA =input.nextdouble (); Doubleb =input.nextdouble (); Doublec =input.nextdouble (); DoubleD =input.nextdouble (); DoubleE =input.nextdouble (); Doublef =input.nextdouble (); DoubleFM = A * D-b *C; if(fm = = 0) {System.out.println ("The equation has no solution"); } Else{System.out.println ("A Is" + ((E * d-b * f)/FM) + "and Y are" + ((A * F-E * c)/FM)); }    }}

3.4

 Public classTest { Public Static voidMain (string[] args) {Scanner input=NewScanner (system.in); intA = (int) (Math.random () * 100); intB = (int) (Math.random () * 100); System.out.print ("Enter the sum of the 0~100:" + A + "and" + B + ":"); intc =Input.nextint (); if(c = = A +b) System.out.println ("True"); ElseSystem.out.println ("False"); }}

3.5

 Public classTest { Public Static intJudgeintYearintmonth) {        BooleanLeap; Leap= (year% of 4 ==0 && year% 100! = 0) | | (Year% 400 = = 0); if(Month = = 2) {            if(LEAP)return29; Else return28; } Else if(Month = = 1 | | month = = 3 | | month = = 5 | | month = = 7 | | month = 8 | | month = = | | month = = 12) {            return31; } Else {            return30; }    }     Public Static voidMain (string[] args) {string[] months= {"", "January", "February", "March", "April",                "May", "June", "July", "August", "September",                "October", "November", "December"}; System.out.print ("Inpit Month and Year:"); Scanner input=NewScanner (system.in); intmonth =Input.nextint (); intYear =Input.nextint (); System.out.println (Months[month]+ "" + year + "have" + judge (year, month) + "Days"); }}

4.7

 Public classTest { Public Static voidMain (string[] args) {Doublen = 10000; Doubles1, S2, t; S1= S2 = 0; T= 1; Final DoubleRate = 0.05;  for(inti = 1; I < 11; i++) {T*= (1 +Rate ); } S1= n *T; System.out.println ("S1 =" +S1); }}

4.16

 Public classTest { Public Static voidMain (string[] args) {System.out.print ("Enter A number:"); Scanner input=NewScanner (system.in); intn =Input.nextint (); inti = 2;  while(true) {             while(n% i = = 0 && n! =i) {System.out.print (i+ ", "); N/=i; } I++; if(n = =i) {System.out.println (i);  Break; }        }    }}

4.25

 Public classTest { Public Static DoubleCOUNTPI (intN) {DoublePI = 0; DoubleT; intM=1;  for(inti = 1; I < n; i++) {T=1.0/(2*i-1); T*=m; Pi+=T; M*=-1; } Pi*= 4; returnPi; }         Public Static voidMain (string[] args) {System.out.print ("Enter A number:"); Scanner input=NewScanner (system.in);  for(inti = 10000; I <= 100000; i++) {System.out.println ("Pi (" + i + ") =" +COUNTPI (i)); }    }}

4.27

 Public classTest { Public Static BooleanIsleapyear (intN) {return((n% 4 = = 0 && n% = 0) | | n 400 = = 0); }         Public Static voidMain (string[] args) {intn = 0;  for(inti = 2001; I < 2100; i++) {            if(Isleapyear (i)) {n++; if(n% 11 = = 0) {System.out.println ("\ n"); } Else{System.out.print (i+ " "); }                            }        }    }}

4.33

 Public classTest { Public Static BooleanTestintN) {inti, sum; intm = N/2; Sum= 0;  for(i = 1; I <= m; i++) {            if(n% i = = 0) Sum+=i; }        if(Sum = =N)return true; Else            return false; }     Public Static voidMain (string[] args) { for(inti = 2; I < 10000; i++) {            if(Test (i)) System.out.print (i+ "\ n"); }    }}

4.41

 Public classTest { Public Static voidMain (string[] args) {intN, Count, Max, T; Scanner input=NewScanner (system.in); System.out.println ("Enter A number:"); N=Input.nextint (); T= max =N; Count= 0;  while(T! = 0) {            if(T >max) {Count= 1; Max=T; } Else{Count++; } System.out.println ("Enter A number:"); T=Input.nextint (); } System.out.println ("max=" + Max + ", count=" +count); }}

Programming exercises for the 3rd and 4 chapters of Java language programming