左右扫描找最大

CodingProgrammer · web-flow · commit 93505bc893cc · 2020-12-07T20:46:00.000+08:00
diff --git a/每日一题/42接雨水.py b/每日一题/42接雨水.py
@@ -0,0 +1,114 @@
+'''
+Descripttion: 给定 n 个非负整数表示每个宽度为 1 的柱子的高度图，计算按此排列的柱子，下雨之后能接多少雨水。
+version: 1
+Author: Jason
+Date: 2020-12-07 10:35:20
+LastEditors: Jason
+LastEditTime: 2020-12-07 16:10:25
+'''
+
+
+from typing import List
+import random
+
+
+def GenerateRandomList(number, size):
+    temp = list()
+    random_legth = random.randint(0, size)
+    current_length = 0
+    while current_length < random_legth:
+        temp.append(random.randint(1, number))
+        current_length += 1
+    return temp
+
+
+class Solution:
+    def trap(self, height: List[int]):
+        left = 0
+        right = len(height) - 1
+        lower = 0
+        level = 0
+        res = 0
+        while left < right:
+            if height[left] < height[right]:
+                lower = height[left]
+                left += 1
+            else:
+                lower = height[right]
+                right -= 1
+            level = lower if lower > level else level
+            res += (level - lower)
+        return res
+
+    def trap2(self, height: List[int]):
+        '''
+        func: 按行求
+        param {*}
+        return {*}
+        '''
+        length = len(height)
+        res = 0
+        for index in range(1, length - 1):
+            leftMax = 0
+            for index_left in range(index):
+                if height[index_left] > leftMax:
+                    leftMax = height[index_left]
+            rightMax = 0
+            for index_right in range(index + 1, length):
+                if height[index_right] > rightMax:
+                    rightMax = height[index_right]
+            lower = min(leftMax, rightMax)
+            if lower > height[index]:
+                res += (lower - height[index])
+        return res
+
+    def trap3(self, height: List[int]):
+        '''
+        func: 从左往右扫一遍，找到每一个值左侧的最大；从右往左扫一遍，找到每一个数右侧最大的值，
+        param {*}
+        return {*}
+        '''
+        length = len(height)
+        if length < 3:
+            return 0
+        leftMax = [0]
+        rightMax = [0]
+        point_left = 1
+        point_right = length - 2
+        while point_left < length:
+            # 添加leftMax
+            if height[point_left - 1] > leftMax[-1]:
+                leftMax.append(height[point_left - 1])
+            else:
+                leftMax.append(leftMax[-1])
+
+            # 添加rightMax
+            if height[point_right + 1] > rightMax[-1]:
+                rightMax.append(height[point_right + 1])
+            else:
+                rightMax.append(rightMax[-1])
+
+            point_left += 1
+            point_right -= 1
+
+        res = 0
+        for i in range(length):
+            lower = min(leftMax[i], rightMax[length - 1 - i])
+            if lower > height[i]:
+                res += (lower - height[i])
+        return res
+
+
+s = Solution()
+for _ in range(100):
+    li = GenerateRandomList(20, 20)
+    if len(li) < 1:
+        continue
+    res1 = s.trap(li)
+    res2 = s.trap2(li)
+    res3 = s.trap3(li)
+    if res1 != res3:
+        print("*********************************")
+        print("Wrong")
+        print(li)
+print("Done")
