2026.2.9 K次取反最大数组和 & 加油站 & 分发糖果

多打代码2026-02-10 10:29

python 复制代码

class Solution:
    def largestSumAfterKNegations(self, nums: List[int], k: int) -> int:
        res = 0
        nums.sort()
        min_num = float('inf')

        for i in range(len(nums)):
            if nums[i] >= 0:
                res += nums[i]
                min_num = min(min_num, nums[i])
            else:
                if k > 0:
                    res += nums[i] * -1
                    k -= 1
                    min_num = min(min_num, -1 * nums[i])
                else:
                    res += nums[i]
        if k > 0 and k % 2:
            res -= 2 * min_num
        
        return res

134. 加油站

python 复制代码

class Solution:
    def canCompleteCircuit(self, gas: List[int], cost: List[int]) -> int:
        total_sum = 0 # 记录总剩余油量
        start = 0 # 汽车开始位置
        cur_sum = 0 # 从start开始的当前剩余油量
        n = len(gas)
        for i in range(n):
            dif = gas[i] - cost[i]
            total_sum += dif
            cur_sum += dif
            if cur_sum < 0:
                start = i + 1
                cur_sum = 0
        
        if total_sum < 0:
            return -1         

        return start

135. 分发糖果

python 复制代码

class Solution:
    def candy(self, ratings: List[int]) -> int:
        n = len(ratings)
        candies = [1] * n
        
        # 1. 从左向右遍历：处理右边比左边评分高的情况
        for i in range(1, n):
            if ratings[i] > ratings[i - 1]:
                candies[i] = candies[i - 1] + 1
        
        # 2. 从右向左遍历：处理左边比右边评分高的情况
        for i in range(n - 2, -1, -1):
            if ratings[i] > ratings[i + 1]:
                # 贪心：取最大值以同时满足左右约束
                candies[i] = max(candies[i], candies[i + 1] + 1)
        
        return sum(candies)