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| import java.util.*;
public class JBT2501 {
public static void main(String[] args) {
myMath mymath = new myMath();
int choice = 1;
int i = 0, m = 0, n = 0;
long sum = 0, fact = 0, p = 0;
Scanner stdin = new Scanner(System.in);
while (choice != 0) {
System.out.println("\n\n");
System.out.println("主要功能");
System.out.println("========================");
System.out.println("1.输出1+2+...+n的结果");
System.out.println("2.输出1*2*...*n的结果");
System.out.println("3.输出两个整数的最大值");
System.out.println("4.求使得1+2+...+n的值大于p的最小n值");
System.out.println("5.求m和n的之间的素数");
System.out.println("6.退出系统");
System.out.print("选择[1..6]：");
choice = stdin.nextInt();
System.out.println("");
switch (choice) {
case 1:
System.out.print("请输入n:");
n = stdin.nextInt();
System.out.println("");
System.out.println("sum(1.." + n + ")=" + mymath.sum(n));
break;
case 2:
System.out.print("请输入n:");
n = stdin.nextInt();
System.out.println("");
System.out.println(n + "!=" + mymath.fact(n));
break;
case 3:
System.out.print("请输入m:");
m = stdin.nextInt();
System.out.println("");
System.out.print("请输入n:");
n = stdin.nextInt();
System.out.println("");
System.out.println("max(" + m + "," + n + ")=" + mymath.max(m, n));
break;
case 4:
System.out.print("请输入p:");
p = stdin.nextInt();
System.out.println("");
System.out.println("(1+2+..+n)>=" + p + "的最小n=" + mymath.minN(p));
break;
case 5:
System.out.print("请输入m:");
m = stdin.nextInt();
System.out.println("");
System.out.print("请输入n:");
n = stdin.nextInt();
System.out.println("");
mymath.dispPrimeNumber(m, n);
break;
case 6:
System.out.println("退出系统......");
return;
}
}
}
}
class myMath {
long sum(int n) {
long sum1 = 0;
int i;
for (i = 1; i <= n; i++) {
sum1 = sum1 + i;
}
return sum1;
}
long fact(int n) {
long fact1 = 1;
int i;
for (i = 1; i <= n; i++) fact1 = fact1 * i;
return fact1;
}
int max(int x, int y) {
return x > y ? x : y;
}
int minN(long m) {
long sum = 0;
int n = 0;
while (sum < m) {
sum = sum + n;
n = n + 1;
}
return n;
}
void dispPrimeNumber(int num1, int num2) {
int m, i, k, num = 0;
boolean isprime = true;
System.out.printf("\n");
for (m = num1; m <= num2; m++) {
k = (int) Math.sqrt(m + 1);
for (i = 2; i <= k; i++)
if (m % i == 0) {
isprime = false;
break;
}
if (isprime) {
System.out.printf("%-4d", m);
num++;
if (num % 10 == 0) System.out.printf("\n");
}
isprime = true;
}
System.out.printf("\n[%d：%d]之间素数总共%d\n", num1, num2, num);
}
}
|