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.
Input: n = 5 Output: 2 Explanation: Because the 3rd row is incomplete, we return 2.
Input: n = 8 Output: 3 Explanation: Because the 4th row is incomplete, we return 3.
1 <= n <= 231 - 1
class Solution: def arrangeCoins(self, n: int) -> int: if n==1: return 1 l=0 r=n//2 + 1 while l<=r: m = l+(r-l)//2 x = (m*(m+1)//2) if x==n: return(m) elif x<n: l = m+1 else: r=m-1 return(l-1)