递归求和

#include <stdio.h>int sum(int n){if(n==1)return n;return n+sum(n-1);}void main(){int n,c;scanf("%d",&n);c=sum(n);printf("%d\n",c);}方法二：#include <stdio.h>int sum(int a,int b){if(a==b)return a;return a+sum(a+1,b);}void main(){int a,b,c;scanf("%d%d",&a,&b);c=sum(a,b);printf("%d\n",c);}