ZeroJudge C164: Golden Coins

The king pays loyal knights in gold coins. On the first day, a knight receives one coin; then, for the next two days (the second and third days), they receive two coins each day. This pattern continues, with the knight receiving one additional coin each day for the following consecutive days, forming an increasing sequence. This payment scheme persists: after receiving N coins for N consecutive days, the knight will receive N+1 coins for the next consecutive N+1 days.

Please calculate the total amount of gold coins the knight has earned in the previous K days.

Sample Inputs/Outputs

Thought Process

可以先將每一天會發放的金幣數量紀錄起來。跑一個 For迴圈 從 0 到 1000000，在迴圈外面宣告一個 count 變數預設為 1，代表發放的金幣數量。在迴圈中再跑一個 For迴圈 從 0 到 count – 1，並將 count 進行 Push_Back 至一個 Vector 中。Push_Back 的迴圈結束後要將最外層的 For迴圈的 i += count，並且將 count++。

Iterate through Vector:
For loop: Execute a for loop from 0 to K-1, where K is the number of days for which gold coins were awarded.
Initialize sum variable:
Declare ans: Declare a variable named ans and initialize it to 0. This variable will store the cumulative sum of gold coins.
Accumulate gold coins:
Add Vector element: Within the for loop, add the ith element of the previously declared Vector to the value of ans. This effectively sums up the gold coins for each day.

Sample Code－ZeroJudge C164: Golden Coins

#include <iostream>
#include <vector>
using namespace std;

int main() {
    cin.sync_with_stdio(0);
    cin.tie(0);
    int N, count = 1, ans = 0;
    cin >> N;
    vector<int>num;
    for (int i = 0; i<1000000; i++) {
        for (int j = 0; j<count; j++) num.push_back(count);
        i += count;
        count++;
    }
    for (int i = 0; i<N; i++) ans += num[i];
    cout << ans << "\n";
}

//ZeroJudge C164
//Dr. SeanXD