update

Author: wuduhren

problems/python3/detect-squares.py

@@ -0,0 +1,22 @@
+class DetectSquares:
+
+    def __init__(self):
+        self.store = collections.Counter()
+
+    def add(self, point: List[int]) -> None:
+        self.store[tuple(point)] += 1
+
+    def count(self, point: List[int]) -> int:
+        x, y = point
+        ans = 0
+        
+        for dx, dy in self.store:
+            if abs(x-dx)!=abs(y-dy) or x==dx or y==dy: continue
+            ans += self.store[(dx, dy)]*self.store[(dx, y)]*self.store[(x, dy)]
+        return ans
+
+
+# Your DetectSquares object will be instantiated and called as such:
+# obj = DetectSquares()
+# obj.add(point)
+# param_2 = obj.count(point)

problems/python3/happy-number.py

@@ -0,0 +1,17 @@
+class Solution:
+    def isHappy(self, n: int) -> bool:
+        def digitSquare(n) -> int:
+            ans = 0
+            while n>0:
+                ans += (n%10)**2
+                n = n//10
+            return ans
+
+        visited = set()
+        visited.add(1)
+
+        while n not in visited:
+            visited.add(n)
+            n = digitSquare(n)
+
+        return n==1

problems/python3/multiply-strings.py

@@ -0,0 +1,22 @@
+class Solution:
+    def multiply(self, num1: str, num2: str) -> str:
+        if num1=='0' or num2=='0': return '0'
+        M, N = len(num1), len(num2)
+        temp = [0]*(M+N+1)
+
+        num1, num2 = num1[::-1], num2[::-1]
+        for i in range(M):
+            for j in range(N):
+                digits = int(num1[i])*int(num2[j])
+                temp[i+j] += digits
+                temp[i+j+1] += temp[i+j]//10
+                temp[i+j] = temp[i+j]%10
+        
+        ans = ''
+        temp = temp[::-1]
+        isLeadingZero = True
+        for d in temp:
+            if d!=0 or not isLeadingZero:
+                isLeadingZero = False
+                ans += str(d)
+        return ans

problems/python3/plus-one.py

@@ -0,0 +1,16 @@
+class Solution:
+    def plusOne(self, digits: List[int]) -> List[int]:
+        i = len(digits)-1
+        needAdditionDigit = True
+
+        while i>=0 and needAdditionDigit:
+            if digits[i]==9:
+                digits[i] = 0
+                i -= 1
+                needAdditionDigit = True
+            else:
+                digits[i] += 1
+                needAdditionDigit = False
+        if needAdditionDigit: digits.insert(0, 1)
+        return digits
+        

problems/python3/powx-n.py

@@ -0,0 +1,14 @@
+class Solution:
+    def myPow(self, x: float, k: int) -> float:
+        if k<0: return 1/self.myPow(x, -k)
+
+        if k==0:
+            return 1
+        elif k==1:
+            return x
+        elif k%2==0:
+            half = self.myPow(x, k//2)
+            return half * half
+        else:
+            half = self.myPow(x, (k-1)//2) 
+            return half * half * x