public class SumN { public static void main(String []args){ System.out.print(sum(100)); } // static int sum=0; public static int sum(int n){ if(n==1) { return 1; }else { return n+sum(n-1); //这里是自变量+函数 } } public static int recursion(int i) { if(i==1) { return 1; }else { return i+recursion(i-1); //这里是自变量+函数 } } }