#include<stdio.h> int main() { int n; int sum(int n); scanf("%d",&n); printf("%d\n",sum(n)); } int sum(int n) { int b; if(n>0) b=sum(n-1)+2*n-1; return(b); }
#include<stdio.h> int main() { int n; int sum(int n); scanf("%d",&n); printf("%d\n",sum(n)); } int sum(int n) { int b; if(n>1) b=sum(n-1)+2*n-1; if(n==1) b=1; return b;} 你没有首项追问