Codeforces Round #498 (Div. 3)

Your task is to split this array into three parts (some of which may be empty) in such a way that each element of the array belongs to exactly one of the three parts, and each of the parts forms a consecutive contiguous subsegment (possibly, empty) of the original array.

Let the sum of elements of the first part be $\mathrm{sum1sum1\; ,\; the\; sum\; of\; elements\; of\; the\; second\; part\; be\; sum2sum2\; and\; the\; sum\; of\; elements\; of\; the\; third\; part\; be\; sum3sum3\; .\; Among\; all\; possible\; ways\; to\; split\; the\; array\; you\; have\; to\; choose\; a\; way\; such\; that\; sum1=sum3sum1=sum3\; and\; sum1sum1\; is\; maximum\; possible.}$

More formally, if the first part of the array contains $\mathrm{aa\; elements,\; the\; second\; part\; of\; the\; array\; contains\; bb\; elements\; and\; the\; third\; part\; contains\; cc\; elements,\; then:}$

$$\mathrm{sum1=\sum 1\le i\le adi,sum1=\sum 1\le i\le adi,\; sum2=\sum a+1\le i\le a+bdi,sum2=\sum a+1\le i\le a+bdi,\; sum3=\sum a+b+1\le i\le a+b+cdi.sum3=\sum a+b+1\le i\le a+b+cdi.}$$

The sum of an empty array is $\mathrm{00\; .}$

Your task is to find a way to split the array such that $\mathrm{sum1=sum3sum1=sum3\; and\; sum1sum1\; is\; maximum\; possible.}$