HackMD
918.Maximum Sum Circular Subarray
tags: Medium,Array,DP,Divide and Conquer,Queue
918. Maximum Sum Circular Subarray
題目描述
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.
範例
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
解答
C++
class Solution {
public:
int maxSubarraySumCircular(vector<int>& nums) {
int curMax = INT_MIN, maxSum = 0, curMin = INT_MAX, minSum = 0, total = 0;
for (auto n : nums) {
maxSum = max(maxSum, 0) + n;
curMax = max(curMax, maxSum);
minSum = min(minSum, 0) + n;
curMin = min(curMin, minSum);
total += n;
}
return curMax > 0 ? max(curMax, total - curMin) : curMax;
}
};
Yen-Chi ChenThu, Jan 19, 2023
