You have a total of n coins that you want to form in a staircase shape, where every k-th row must have exactly k coins. Given n, find the total number of full staircase rows that can be formed. n is a non-negative integer and fits within the range of a 32-bit signed integer. Example 1: n = 5
The coins can form the following rows: ¤ ¤ ¤ ¤ ¤
Because the 3rd row is incomplete, we return 2.
Example 2: n = 8
The coins can form the following rows: ¤ ¤ ¤ ¤ ¤ ¤ ¤ ¤
Because the 4th row is incomplete, we return 3. 方法一：
class Solution {public: int arrangeCoins(int n) { int i; for (i=1; n>=0; ++i){ n -= i; } return i - 2; }};方法二: 利用等差数列求和公式，并且注意要先将n转化为double类型
class Solution {public: int arrangeCoins(int n) { return (-1 + sqrt(8 * (double)n + 1) )/ 2; }};新闻热点
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