add 772 py3

Author: fxrcode

solution/0700-0799/0772.Basic Calculator III/README.md

@@ -73,7 +73,34 @@ tags:
 #### Python3
 
 ```python
-
+class Solution:
+    def calculate(self, s: str) -> int:
+        def dfs(q):
+            num, sign = 0, "+"
+            stk = []
+            while q:
+                c = q.popleft()
+                if c.isdigit():
+                    num = num * 10 + int(c)
+                if c == "(":
+                    num = dfs(q)
+                if c in "+-*/)" or not q:
+                    #! careful we catch ')' to eval (...), ow  (4-5/2) will only be sum([4,-5]) => -1, /2 is ignored
+                    if sign == "+":
+                        stk.append(num)
+                    elif sign == "-":
+                        stk.append(-num)
+                    elif sign == "*":
+                        stk.append(stk.pop() * num)
+                    elif sign == "/":
+                        stk.append(int(stk.pop() / num))
+                    sign = c
+                    num = 0
+                if c == ")":
+                    break
+            return sum(stk)
+
+        return dfs(deque(s))
 ```
 
 #### Java