题解 | #分糖果问题#

O(n), O(1), slope算法。重点：

if down >= peak:
    res += 1      

这一部分考虑了下降超过上升数的情况

#
# pick candy
# @param arr int整型一维数组 the array
# @return int整型
#
class Solution:
    def candy(self , arr ):
        # write code here
        n = len(arr)
        up, down = 0, 0
        res, peak = 1, 1
        print(0, up, down, peak, res)
        for i in range(1, n):

            if arr[i] > arr[i-1]:
                down=0
                up += 1
                res += up+1
                peak = up+1
            elif arr[i] < arr[i-1]:
                up=0
                down += 1
                res += down
                if down >= peak:
                    res += 1                
            else:
                res += 1
                peak = 1
                up, down = 0, 0
            print(i, up, down, peak, res)
        return res