Leetcode 918. Maximum Sum Circular Subarray (滑动窗口+单调队列好题)

  1. Maximum Sum Circular Subarray
    Medium

Given a circular integer array nums of length n, return the maximum possible sum of a non-empty subarray of nums.

A circular array means the end of the array connects to the beginning of the array. Formally, the next element of nums[i] is nums[(i + 1) % n] and the previous element of nums[i] is nums[(i - 1 + n) % n].

A subarray may only include each element of the fixed buffer nums at most once. Formally, for a subarray nums[i], nums[i + 1], ..., nums[j], there does not exist i <= k1, k2 <= j with k1 % n == k2 % n.

Example 1:

Input: nums = [1,-2,3,-2]

Output: 3

Explanation: Subarray [3] has maximum sum 3.

Example 2:

Input: nums = [5,-3,5]

Output: 10

Explanation: Subarray [5,5] has maximum sum 5 + 5 = 10.

Example 3:

Input: nums = [-3,-2,-3]

Output: -2

Explanation: Subarray [-2] has maximum sum -2.

Constraints:

n == nums.length

1 <= n <= 3 * 104

-3 * 104 <= nums[i] <= 3 * 104

解法1:

不用滑动窗口和单调队列。实际上我们找连续子数组最大和 与 sum - 连续子数组最小和 之间的最大值就可以了。

cpp 复制代码
class Solution {
public:
    int maxSubarraySumCircular(vector<int>& nums) {
        int sum = 0, currMaxSum = 0, currMinSum = 0;
        int gMaxSum = INT_MIN, gMinSum = INT_MAX;
        for (auto num : nums) {
            sum += num;
            currMaxSum = max(currMaxSum + num, num);
            gMaxSum = max(gMaxSum, currMaxSum);
            currMinSum = min(currMinSum + num, num);
            gMinSum = min(gMinSum, currMinSum);
        }
        //if all negative
        if (gMinSum == sum) return gMaxSum;
        return max(gMaxSum, sum - gMinSum);
    }
};

解法2:滑动窗口 + 单调队列

相关推荐
Jelena技术达人10 分钟前
淘宝/天猫按图搜索(拍立淘)item_search_img API接口实战指南
算法·图搜索算法
Adorable老犀牛21 分钟前
阿里云-基于通义灵码实现高效 AI 编码 | 8 | 上手实操:LeetCode学习宝典,通义灵码赋能算法高效突破
学习·算法·leetcode
望获linux26 分钟前
【实时Linux实战系列】规避缺页中断:mlock/hugetlb 与页面预热
java·linux·服务器·数据库·chrome·算法
菜就多练,以前是以前,现在是现在27 分钟前
Codeforces Round 1048 (Div. 2)
数据结构·c++·算法
失散131 小时前
分布式专题——9 Redis7底层数据结构解析
java·数据结构·redis·分布式·缓存·架构
林木辛1 小时前
LeetCode 热题 160.相交链表(双指针)
算法·leetcode·链表
野生的编程萌新1 小时前
【C++深学日志】从0开始的C++生活
c语言·开发语言·c++·算法
ulias2122 小时前
单元最短路问题
数据库·c++·算法·动态规划
崎岖Qiu2 小时前
leetcode380:RandomizedSet - O(1)时间插入删除和获取随机元素(数组+哈希表的巧妙结合)
java·数据结构·算法·leetcode·力扣·散列表
ZLRRLZ2 小时前
【数据结构】图
数据结构·算法·图论