Day009 circular structure (exercise)

seek 100 All prime numbers within

（ prime number ： One is greater than 1 The natural number of , except 1 And it itself , Cannot be divided by other natural numbers ）

package cn.bdqn.demo03;

public class Practice {

public static void main(String[] args) {

/*

 * seek 100 All prime numbers within （ prime number ： One is greater than 1 The natural number of , except 1 And it itself , Cannot be divided by other natural numbers ）

 */

// Initial value

int i = 2;

while (i <= 100) {

boolean flag = true;

for(int j = 2; j < i; j++) {

if (i % j == 0) {

flag = false;

break;

}

}

if (flag) {

System.out.println(i);

}

i++;

}

}

}

Write a method , This method implements output 100-999 Between the number of daffodils .

package cn.bdqn.demo03;

public class Practice02 {

public static void main(String[] args) {

// Write a method , This method implements output 100-999 Between the number of daffodils .

int i= 100;

while(i<=999){

int a = i%10;

int b = i/10%10;

int c = i/100%10;

if(a*a*a+b*b*b+c*c*c==i){

System.out.println(i);

}

i++;

}

}

}

Find out 1-1/2+1/3-1/4…..1/100 And

package cn.bdqn.demo03;

public class Practice05 {

public static void main(String[] args) {

// Find out 1-1/2+1/3-1/4…..-1/100 And

int i = 1;

double sum = 0;

while (i <= 100) {

double a = -(1.0 / i);// i As denominator

if (i % 2 == 0) {

a = -(1.0 / i);

} else {

a = 1.0 / i;

}

sum += a;

i++;

}

System.out.println(sum);

}

}

Output the multiplication table

package cn.bdqn.demo03;

public class Practice11 {

public static void main(String[] args) {

// Output the multiplication table

for (int i = 1; i <= 9; i++) {

for (int j = 1; j <= 9; j++) {

if (j <= i) { // When i=1 when ,j=1, Meet the conditions , Execute output at this time , After execution j Self adding ,(j=2)>(i=1), Not meeting the conditions , Jump out of ;

         // here i Self adding ,i=2, Enter again j Of for loop , here 1<2 Meet the conditions , Execution output 1*2=2, After execution j Self adding ,

 //j=2, Satisfy j<=i, Execution output 2*2=4, After execution j Self adding ,j=3, here j<=i Don't set up , Out of the loop ; By analogy

System.out.print(j + "*" + i + "=" + (j * i) + " ");

//j==i Change the line , Realize the format of multiplication table

if (j == i) {

System.out.println(" ");

}

}

}

}

}

}