帮忙做个题目吧 大神们啊！

求大神们做一下这几道题目吧，希望简洁明了，能运行！谢了！
[解决办法]
用递归求和

int add ( int cur, int n )
{
  if ( cur==n ) return 0;
  return cur*cur + add(cur+1,n);
}

#include<stdio.h>
int run[12] = {31,29,31,30,31,30,31,31,30,31,30,31}; 
int ping[12] = {31,28,31,30,31,30,31,31,30,31,30,31}; 
int puanduan(int nian)
{
int x = 1 ; 
 if(nian%100==0) 
 {  
 if(nian%400==0)   
 x=0; 
 }
else if(nian%4==0)  
 x=0; 
 
return x;
} 
int main(void)
{
int i,year,mon,day,year1,mon1,day1,m = 0,n = 0,as,zong = 0,tian;
 char s;
 /*
 输入年月日 
 */
 printf("输入起始时间（年.月.日）：");
 scanf("%d.%d.%d",&year,&mon,&day); 
 printf("输入终止时间（年.月.日）：");
 s = getchar();
 scanf("%d.%d.%d",&year1,&mon1,&day1);
 
 /*
 判断这中间又几个闰年，几个平年，闰年n+1,平年m+1
 
 */
 for(i = year+1;i < year1;i++)
 {
  as = puanduan(i);
  if(as == 1)
   m++;
  else
   n++;
 }
 tian = m * 365 + n * 366;
 /*
 给总天数加上year年的天数 
 */ 
 if(puanduan(year))
 {
  for(i = 0;i < mon;i++)
  {
   zong = zong + ping[i];
  }
  zong = 365 - zong;
}
else
{
  for(i = 0;i < mon;i++)
  {
   zong = zong + run[i];
  }
  zong = 366 - zong;
}
tian = tian + zong;
/*
 给总天数加上year1年的天数 
 */ 
 if(puanduan(year1))
 {
  for(i = 0;i < mon;i++)
  {
   zong = zong + ping[i];
  }
}
else
{
  for(i = 0;i < mon;i++)
  {
   zong = zong + run[i];
  }
}
tian = tian + zong;
  
  printf("%d年%d月%d日到%d年%d月%d日总共有%d天\n",year,mon,day,year1,mon1,day1,tian); 
  
 return 0;
}