首先最左边和最右边肯定无法蓄水
考虑能蓄水的情况:左右两边的高度都大于height[i]
所以得左右遍历找到heigh[i]时的左右最大值
再遍历height 当min(maxL[i],maxR[i])>height[i]即能蓄水
class Solution:
def trap(self, height):
"""
:type height: List[int]
:rtype: int
"""
n = len(height)
if n<3:return 0
right=[0]*n
maxR=height[-1]
for j in range(n-2,-1,-1):
if height[j]>maxR:
maxR=height[j]
right[j]=maxR
res=0
maxL=height[0]
for i in range(1,n-1,1):
if height[i]>maxL:
maxL=height[i]
elif min(maxL,right[i])>height[i]:
res+=min(maxL,right[i])-height[i]
return res