Maximum Subarray

Description

Given an array of integers, find a contiguous subarray which has the largest sum.

Notice
The subarray should contain at least one number.

Example
Given the array [−2,2,−3,4,−1,2,1,−5,3], 
the contiguous subarray [4,−1,2,1] has the largest sum = 6.

Challenge
Can you do it in time complexity O(n)?

Link

Lintcode_ladder

Method

1. keep tracking the running sum,
   keeping tacking the max running sum for current and previous,
   Once the current running sum < 0, running sum = 0, recaculate the running sum for rest
2. x

Example

1. 1

class Solution {
public:    
    /**
     * @param nums: A list of integers
     * @return: A integer indicate the sum of max subarray
     */
    int maxSubArray(vector<int> nums) {
        // write your code here
        if (nums.empty()) {
            return -1;
        }
        int n = nums.size();
        int sum = 0;
        int maximum = INT_MIN;
        for (int i = 0; i < n; ++i) {
            sum += nums[i];
            maximum = max(maximum, sum);
            sum = max(sum, 0);
        }
        return maximum;
    }
};

Similar problems

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Tags

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