Maximum Subarray Difference

Description:

Given an array with integers.

Find two non-overlapping subarrays A and B, which |SUM(A) - SUM(B)| is the largest.

Return the largest difference.

Example

For [1, 2, -3, 1], return 6

Note

The subarray should contain at least one number

Solution:

( 不难证明这两个子数组必然是紧邻的 )

class Solution {
public:
/**
* @param nums: A list of integers
* @return: An integer indicate the value of maximum difference between two
* Subarrays
*/
int maxDiffSubArrays(vector nums) {
auto sz = (int)nums.size();
if (sz == 0) return 0;
vector minl(sz, nums[0]);
vector maxl(sz, nums[0]);
vector minr(sz, nums[sz-1]);
vector maxr(sz, nums[sz-1]);
for (int i = 1; i < sz; ++i) {
minl[i] = min(minl[i-1]+nums[i], nums[i]);
maxl[i] = max(maxl[i-1]+nums[i], nums[i]);
minr[sz-1-i] = min(minr[sz-i]+nums[sz-1-i], nums[sz-1-i]);
maxr[sz-1-i] = max(maxr[sz-i]+nums[sz-1-i], nums[sz-1-i]);
}
int rc = 0;
for (int i = 0; i < sz-1; ++i)
rc = max(max(rc, maxr[i+1]-minl[i]), maxl[i]-minr[i+1]);
return rc;
}
};