排序

CodingProgrammer · web-flow · commit c17a341d62c4 · 2020-11-29T14:32:37.000+08:00
diff --git a/每日一题/976三角形的最大周长.py b/每日一题/976三角形的最大周长.py
@@ -0,0 +1,83 @@
+'''
+Descripttion:  三角形的最大周长
+version: 1
+Author: Jason
+Date: 2020-11-29 13:36:03
+LastEditors: Jason
+LastEditTime: 2020-11-29 14:31:19
+'''
+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 largestPerimeter(self, A: List[int]) -> int:
+        length = len(A)
+        if length < 3:
+            return 0
+        A.sort()
+        res = 0
+        # 倒序遍历
+        for i in range(length - 1, 1, -1):
+            second = i - 1
+            third = i - 2
+            if second > -1 and third > -1:
+                if A[second] + A[third] <= A[i]:
+                    continue
+
+                # if A[i] - A[second] >= A[third] or A[i] - A[third] > A[second] or A[second] - A[third] >= A[i]:
+                if A[i] - A[third] > A[second]:
+                    continue
+
+                temp_sum = A[i] + A[second] + A[third]
+                if temp_sum > res:
+                    res = temp_sum
+                    # 因为是从后往前遍历，所以找到的第一个就是最大的
+                    break
+        return res
+
+    def largestPerimeter2(self, A: List[int]) -> int:
+        if len(A) < 3:
+            return 0
+        from itertools import combinations
+        res = 0
+        for each in combinations(A, 3):
+            # 任意两边之和大于第三边
+            if each[0] + each[1] <= each[2]:
+                continue
+            elif each[1] + each[2] <= each[0]:
+                continue
+            elif each[0] + each[2] <= each[1]:
+                continue
+
+            # 任意两边之差小于第三边
+            elif max(each[0], each[1]) - min(each[0], each[1]) >= each[2]:
+                continue
+            elif max(each[0], each[2]) - min(each[0], each[2]) >= each[1]:
+                continue
+            elif max(each[1], each[2]) - min(each[1], each[2]) >= each[0]:
+                continue
+
+            elif sum(each) > res:
+                res = sum(each)
+        return res
+
+
+s = Solution()
+for _ in range(100):
+    li = GenerateRandomList(20, 30)
+    res_stand = s.largestPerimeter2(li)
+    res = s.largestPerimeter(li[::])
+    if res != res_stand:
+        print(li)
+print("Done")
