public static void main(String[] args) { System.out.print("请输入一个不大于100的整数:"); Scanner sc = new Scanner(System.in); int n = sc.nextInt(); int s = 0; for (int i = 1; i <= n; i++) { s += i; } System.out.println(s); }
public static void main(String[] args) { Scanner s = new Scanner(System.in); System.out.println("num"); int m = s.nextInt(); int sum = 0; for(int i=1;i<=m;i++){ sum+=i; } System.out.println(sum); }
第2个回答 2015-01-15
这个效率高些
public static int aaa(int i){ if(i==1) return 1; if(i%2==0){ return (i+1)*(i/2); }else{ return i*(i/2)+i; }