题解 | #求1+2+3+...+n#

class Solution:
    def binmulti(self , n: int , m: int):
        if m == 0:
            return 0
        if m == 1:
            return n
        temp =  m & 1
        m -= temp
        n <<= 1
        m >>= 1
        return (m and self.binmulti(n , m)) + (temp and (n >> 1))
    def Sum_Solution(self , n: int) -> int:
        # write code here
        return self.binmulti(n , n + 1) >> 1