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.
分析:
给定n个硬币,要求第k行放k个硬币,返回n个硬币能摆出的完整的行数有多少。用n依次减去1,2,3。。。行数s++,直到n小于0为止,最后返回--s。
class Solution {
public:
int arrangeCoins(int n) {
int s = 0;
int i = 1;
while(n >= 0)
{
n -= i++;
s++;
}
--s;
return s;
}
};