题解 | 金币

#include <stdio.h>
#include <math.h>
int main() {
    int k;
    int day =1;
    int coin =1;
    int strgedays =coin;
    scanf("%d",&k);
    int sum=0;
    if(k>=1 &&k<=10000)
{
    while(day<=k)
    {
     int adddays=(day+strgedays<=k)?strgedays:(k-day+1);
      sum += coin * adddays;
      day+=adddays;
      coin++;
      strgedays=coin;   
    }
}printf("%d",sum);
    return 0;
}