source: https://leetcode.com/problems/maximum-subarray/
C/C++ Solution to LeetCode problem 53. Maximum Subarray.
Problem
Given an integer array nums
, find the subarray with the largest sum, and return its sum.
Examples
Example 1:
Input: nums = [-2,1,-3,4,-1,2,1,-5,4]
Output: 6
Explanation: The subarray [4,-1,2,1] has the largest sum 6.
Example 2:
Input: nums = [1]
Output: 1
Explanation: The subarray [1] has the largest sum 1.
Example 3:
Input: nums = [5,4,-1,7,8]
Output: 23
Explanation: The subarray [5,4,-1,7,8] has the largest sum 23.
Constraints
1 <= nums.length <= 105
-104 <= nums[i] <= 104
Solution
For this problem, we will use Dynamic Programming.
- Iterate through each number:
- Keep tracking of the sum of elements.
- If at any point the
sum < 0
it is not adding to the result, so, we can reset thesum = 0
. - Update the maximum found.
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class Solution {
public:
int maxSubArray(vector<int>& nums) {
int sum = 0;
int maxSum = INT_MIN;
int j = 0;
while (j<nums.size()) {
if (sum < 0 && nums[j] >= sum)
sum = 0;
sum += nums[j];
maxSum = max(maxSum, sum);
j++;
}
return maxSum;
}
};