Contest 183 (py imp)

1394. Find Lucky Integer in an Array/main.py

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+class Solution:
+    def findLucky(self, arr: List[int]) -> int:
+        d = {}
+        for x in arr:
+            d[x] = d.get(x, 0) + 1
+
+        max_res = -1
+        for k,v in d.items():
+            if k==v and max_res < k:
+                max_res = k
+        return max_res

1394. Find Lucky Integer in an Array/readme.org

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+可以直接调用 collections 模块
+count = collections.Counter(arr)

1395. Count Number of Teams/main.py

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+class Solution:
+    def numTeams(self, rating: List[int]) -> int:
+        res = 0
+        for n in (0, 1):
+            length = len(rating)
+            for i in range(0, length-2):
+                for j in range(i+1, length-1):
+                    for k in range(j+1, length):
+                        if n == 0 and rating[i] < rating[j] < rating[k]:
+                            res+=1
+                        elif n == 1 and rating[i] > rating[j] > rating[k]:
+                            res+=1
+        return res
+

1395. Count Number of Teams/readme.org

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+* Solution
+** 三重循环 O(n^3)
+** 二分
+#+BEGIN_SRC python
+class Solution:
+    def numTeams(self, rating: List[int]) -> int:
+        res = 0
+        for rating2 in [rating, rating[::-1]]:
+            d = []
+            d2 = []
+            for val in rating2:
+                ind = bisect.bisect_right(d, val)
+                d.insert(ind, val)
+                d2.insert(ind, ind)
+                res += sum(d2[:ind])
+
+        return res
+#+END_SRC
+** DP