c119: 10220 - I Love Big Numbers. FYI: https://yunlinsong.blogspot.com/2015/03/c119-10220-i-love-big-numbers.html

c119.c

#include<stdio.h>
// val 存結果。p 紀錄階乘結果。psize 紀錄算到多少階乘。
int val[1001], p[10000], psize = 0;

int main(){
  int i, j, n;

  p[0] = 1;
  val[0] = 1;
  for(i = 1; i <= 1000; i++){
    for(j = 0; j <= psize; j++){
      p[j] *= i;
    }
    // 進位處理
    for(j = 0; j <= psize; j++){
      p[j+1] += p[j]/10; 
      p[j] %= 10;
      val[i] += p[j];
    }
    while(p[psize+1]){
      psize++;
      p[psize+1] += p[psize]/10;
      p[psize] %= 10;
      val[i] += p[psize];
    }
  }
  while(scanf("%d", &n)==1){
    printf("%d\n", val[n]);
  }
  return 0;
}