第 75 场双周赛

• [2220. 转换数字的最少位翻转次数](https://leetcode-cn.com/problems/minimum-bit-flips-to-convert-number/)
• [6034. 数组的三角和](https://leetcode-cn.com/problems/find-triangular-sum-of-an-array/)
• [6035. 选择建筑的方案数](https://leetcode-cn.com/problems/number-of-ways-to-select-buildings/)
• [2223. 构造字符串的总得分和](https://leetcode-cn.com/problems/sum-of-scores-of-built-strings/)

第 75 场双周赛

2220. 转换数字的最少位翻转次数

class Solution:
    def minBitFlips(self, start: int, goal: int) -> int:
        return bin(start ^ goal).count('1')

6034. 数组的三角和

class Solution:
    def triangularSum(self, nums: List[int]) -> int:
        n = len(nums)
        for i in range(n - 1):
            for j in range(n - i -1):
                nums[j] = (nums[j] + nums[j+1]) % 10
        return nums[0]

6035. 选择建筑的方案数

class Solution:
    def numberOfWays(self, s: str) -> int:
        t, n, pre, res = s.count('1'), len(s), 0, 0
        for i, c in enumerate(s):
            if c == '0':
                res += pre * (t - pre)
            else:
                res += (i - pre) * (n - t - i + pre)
                pre += 1
        return res        

2223. 构造字符串的总得分和