2600 구슬게임

#include <stdio.h>
 
int dp[100] = { 0 };
 
int main() {
    int n;
    scanf("%d", &n);
    getchar();
 
    dp[1] = 1;
    dp[2] = 2;
    dp[3] = 4;
 
    for (int i = 4; i <= n; i++) {
        dp[i] = dp[i - 1] + dp[i - 2] + dp[i - 3];
    }
 
    printf("%d", dp[n]);
}