C :

# include <stdio.h>
int main()
{
    int K,N,coin=0;
    scanf("%d",&K);               //输入总天数K
    for(N=1;K-N>=0;K-=N++)       //第1天骑士可获得1枚金币
        coin+=N*N;               //在接下来的连续N天里，骑士每天可获得N枚金币
    printf("%d\n",coin+K*N);   //输出骑士总共可获得的金币数
    return 0;
}

C++ :

#include <iostream>
using namespace std;
int main(){
    int n,i,s = 0,c = 0,k = 1;
    cin>>n;
    for(i = 1;i <= n;i++){
    	//cout<<i<<" "<<k<<endl;
    	s = s + k;
		c++;
    	if(c == k){
    		c = 0;
    		k++;
		}
	}
	
	cout<<s<<endl;
    
} 

Java :

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n=sc.nextInt();
		int count=0;
		int sum=0;
		for(int k=1;true;k++) {
			// k 来控制 每次加的天数
		for(int p=0;p<k;p++) {
			sum=sum+k;
			count++;
			if(count==n) {
				System.out.print(sum);
				
				break;
			}	
			
			
			
			
		}
					
		
		if(count==n) {
			
			break;
		}			
			
			
		}
	}

}

Python :

a=int(input())
if a>=1 and a<=10000:
    coins=0
    days=0
    daystrue=0
    tof=1
    while daystrue<=a:
        days+=1
        for i in range(days):
            if daystrue<a:
                coins+=days
                daystrue+=1
            else:
                tof=0
                break
        if tof==0:
            break
    print(coins)