ha24.py

import sys

def cross(X,Y):
    l = sum = 0
    for i in reversed(X):
        sum = sum + i
        if sum > l:
            l = sum
    r = sum = 0
    for i in Y:
        sum = sum + i
        if sum > r:
            r = sum
    return l+r

def split(A):
    h = len(A)/2
    return A[:h], A[h:]

def max_sum(A):
    if(len(A) < 1):
        return 0
    if(len(A)==1):
        return A[0]
    X,Y = split(A)
    return max(max_sum(X),max_sum(Y),cross(X,Y))

print max_sum([31,-41,59,26,-53,58,97,-93,-23,84])