💛 오늘의 학습 키워드

[이분탐색(이진탐색)] Arranging Coins

📝 문제

문제 설명

You have n coins and you want to build a staircase with these coins. The staircase consists of k rows where the ith row has exactly i coins. The last row of the staircase may be incomplete.

Given the integer n, return the number of complete rows of the staircase you will build.

제한 조건

• 1 <= n <= $2^(31)$ - 1

입출력 예

Example 1

Input: n = 5
Output: 2
Explanation: Because the 3rd row is incomplete, we return 2.

Example 2

Input: n = 8
Output: 3
Explanation: Because the 4th row is incomplete, we return 3.

💬 내 풀이

class Solution {
    public int arrangeCoins(int n) {
        int level = 0;
        int coin = 1;
        while (n >= coin) {
            n -= coin;
            coin++;
            level++;
        }
        return level;
    }
}

💻 내 접근 방법

1. while 문을 돌면서 n에서 하나씩 개수를 빼고, n이 coin보다 크거나 같을때만 레벌을 올린다.
2. 해당 level 을 return 하면 완료다.

💦 회고

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