Problem:
Score : 600 points

Problem Statement

Snuke has an integer sequence A of length N.

He will make three cuts in A and divide it into four (non-empty) contiguous subsequences B, C, D and E.
The positions of the cuts can be freely chosen.

Let P,Q,R,S be the sums of the elements in B,C,D,E, respectively.
Snuke is happier when the absolute difference of the maximum and the minimum among P,Q,R,S is smaller.
Find the minimum possible absolute difference of the maximum and the minimum among P,Q,R,S.

Constraints

4 \leq N \leq 2 \times 10^5

1 \leq A_i \leq 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N
A_1 A_2 ... A_N

Output

Find the minimum possible absolute difference of the maximum and the minimum among P,Q,R,S.

Sample Input 1

5
3 2 4 1 2

Sample Output 1

2

If we divide A as B,C,D,E=(3),(2),(4),(1,2), then P=3,Q=2,R=4,S=1+2=3.
Here, the maximum and the minimum among P,Q,R,S are 4 and 2, with the absolute difference of 2.
We cannot make the absolute difference of the maximum and the minimum less than 2, so the answer is 2.

Sample Input 2

10
10 71 84 33 6 47 23 25 52 64

Sample Output 2

36

Sample Input 3

7
1 2 3 1000000000 4 5 6

Sample Output 3

999999994

Solution in Kotlin (1.3.71) (judge verdict: Accepted)

import kotlin.math.abs
import kotlin.math.max
import kotlin.math.min

fun main() {
    nextIntList()
    val values = nextLongList()
    var sum = 0L
    val estValues = mutableListOf<Long>().apply {
        values.forEach {
            sum += it
            add(sum)
        }
    }.toList()

    fun separate(l: Int, r: Int, base: Long): Triple<Long, Long,Int> {
        var lVal = estValues[l]
        val mid = estValues[r - 1].plus(base).toDouble().div(2)
        var minDiff = abs(mid - lVal)
        var index = l + 1
        while (index < r && minDiff > abs(mid - estValues[index])) {
            lVal = estValues[index]
            minDiff = abs(mid - lVal)
            index++
        }
        val rVal = estValues[r - 1] - lVal
        lVal -= base
        return if (rVal < lVal) {
            Triple(rVal, lVal, index- 1)
        } else {
            Triple(lVal, rVal, index- 1)
        }
    }

    var res = Long.MAX_VALUE
    var li = 0
    var ri = 2
    (2..values.lastIndex.minus(1)).forEach {
        val (lMin, lMax, nli) = separate(li, it, 0)
        val (rMin, rMax,nri) = separate(ri, values.size, estValues[it - 1])
        val v = abs(max(lMax, rMax) - min(lMin, rMin))
        li = nli
        ri = nri
        res = min(res, v)
    }
    println(res)
}

// # Utils
// ## Input
fun next() = readLine()!!
fun nextInt() = next().toInt()
fun nextLong() = next().toLong()
fun nextDouble() = next().toDouble()
fun nextList() = next().split(" ")
fun nextIntList() = next().split(" ").map(String::toInt)
fun nextLongList() = next().split(" ").map(String::toLong)
fun nextDoubleList() = next().split(" ").map(String::toDouble)

// ## Array
inline fun <reified T> sizedArray(size: Int, default: T) = Array(size) { default }
inline fun <reified T> sized2DArray(row: Int, column: Int, default: T) = Array(row) { Array(column) { default } }

// ## mod^-1
//    [NOTE] CANNOT use this for 0, mod, 2mod, 3mod ...(return wrong value)
fun modinv(num: Long, mod: Long): Long {
    var a = num
    var b = mod
    var u = 1L
    var v = 0L
    while (b > 0) {
        val t = a.div(b)
        a -= t * b
        a = b.also { b = a } // swap a and b
        u -= t * v
        u = v.also { v = u } // swap u and v
    }
    u %= mod
    if (u < 0) u += mod
    return u
}

fun gcd(x: Int, y: Int): Int {
    fun innerGcd(x: Int, y: Int): Int {
        return if (x % y == 0) y else innerGcd(y, x % y)
    }
    return if (x >= y) innerGcd(x, y) else innerGcd(y, x)
}

fun gcd(x: Long, y: Long): Long {
    fun innerGcd(x: Long, y: Long): Long {
        return if (x % y == 0L) y else innerGcd(y, x % y)
    }
    return if (x >= y) innerGcd(x, y) else innerGcd(y, x)
}

// classes
class UnionFindTree(val size: Int) {
    private val r = sizedArray(size, -1)
    fun root(x: Int): Int {
        if (r[x] < 0) return x
        return root(r[x])
    }

    fun unite(x: Int, y: Int) {
        var rx = root(x)
        var ry = root(y)
        if (rx == ry) return
        if (r[rx] > r[ry]) {
            rx = ry.also { ry = rx }
        }
        r[rx] += r[ry]
        r[ry] = rx
    }

    fun size(x: Int) = -r[root(x)]

    override fun toString(): String {
        return r.joinToString(separator = ", ")
    }
}