我有一个排列的数组，我想将它分成3个部分，以便它们的总和彼此最接近。
Ex: I have this array:
10, 8, 8, 7, 6, 6, 6, 5
so it'll be divided into 3 part like:
p1 {10,8} sum = 18
p2 {8,7,6} sum = 21
p3 {6,6,5} sum = 17
答案 0 :(得分：9)
原始海报已经有了一个工作解决方案（在评论中注明），将数组分成两部分，数额相等;请拨打此split2。可以使用split2构建三部分版本。
split2将数组拆分为两部分。 split2将其他部分拆分为两部分。 答案 1 :(得分：2)
这就像two-Partition问题，它是NP-Hard，但不是强烈意义上的，你可以有一个O（nK）算法，其中K是输入和的大小，参见pseudo polynomial time algorithm for subset sum，另请参阅我对divide-list-in-two-parts-that-their-sum-closest-to-each-other的回答，但在您的情况下，您应该添加另一个维度来处理它。
答案 2 :(得分：1)
尝试以下代码
int total = 0, partSum = 0, partIndex = 0;
int noOfParts = 3; //Initialize the no. of parts
int[] input = { 10, 8, 8, 7, 6, 6, 6, 5 };
int[] result = new int[noOfParts]; //Initialize result array with no. of locations equal to no. of parts, to store partSums
foreach (int i in input) //Calculate the total of input array values
{
total += i;
}
int threshold = (total / noOfParts) - (total / input.Length) / 2; //Calculate a minimum threshold value for partSum
for (int j = input.Length - 1; j > -1; j--)
{
partSum += input[j]; //Add array values to partSum incrementally
if (partSum >= threshold) //If partSum reaches the threshold value, add it to result[] and reset partSum
{
result[partIndex] = partSum;
partIndex += 1;
partSum = 0;
continue;
}
}
if (partIndex < noOfParts) //If no. of parts in result[] is less than the no. of parts required, add the remaining partSum value
{
result[partIndex] = partSum;
}
Array.Reverse(result);
foreach (int k in result)
{
Console.WriteLine(k);
}
Console.Read();
我已经使用数组中的各种值（按降序排列）测试了这个值，并且使用了不同的值。零件（3,4,5 ......）并取得了良好的效果。
答案 3 :(得分：1)
// calculate total
total = 0;
for(i = 0; i != size; ++i) {
total += array[i];
}
// partition
n_partitions = 3;
current_partition = 1;
subtotal = array[0];
for(i = 1; i != size; ++i) {
if(subtotal + array[i] > total / n_partitions) {
// start new partition;
current_partition++;
subtotal = array[i];
} else {
// push to current partition
subtotal += array[i];
}
}
答案 4 :(得分：0)
更新了代码：
我建议的方法如下（代码如下）：
根据上述逻辑，您将始终添加具有最低总值的输出部分（这将有助于保持相似整体值的部分）。
（在下面的代码示例中，我已跳过数组排序步骤，因为您的示例已经排序）
代码：
// the input array
int[] inputArray = new int[] { 10, 8, 8, 7, 6, 6, 6, 5 };
// the number of parts you want
int numberOfOutputParts = 3;
// create the part structures
List<Part> listOfParts = new List<Part>();
for(int i =0; i < numberOfOutputParts; i++)
{
listOfParts.Add(new Part());
}
// iterate through each input value
foreach (int value in inputArray)
{
// find the part with the lowest sum
int? lowestSumFoundSoFar = null;
Part lowestValuePartSoFar = null;
foreach(Part partToCheck in listOfParts)
{
if (lowestSumFoundSoFar == null || partToCheck.CurrentSum < lowestSumFoundSoFar)
{
lowestSumFoundSoFar = partToCheck.CurrentSum;
lowestValuePartSoFar = partToCheck;
}
}
// add the value to that Part
lowestValuePartSoFar.AddValue(value);
}
上面使用的Part类的代码（尽管你可以使用更好的东西如下）：
public class Part
{
public List<int> Values
{
get;
set;
}
public int CurrentSum
{
get;
set;
}
/// <summary>
/// Default Constructpr
/// </summary>
public Part()
{
Values = new List<int>();
}
public void AddValue(int value)
{
Values.Add(value);
CurrentSum += value;
}
}
答案 5 :(得分：0)
你能试试我的样本，这可能对你有所帮助
我的算法： 1 /通过输出数组的数量计算数组的平均值（exp：值= 3）
2 /对数组求和，直到Sum的最小间隙与平均值相比（以1 /计算）
3 /执行步骤2，直到您到达数组编号的末尾
我使用C＃3.5进行测试
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Collections;
namespace WindowsFormsApplication2
{
public partial class Form2 : Form
{
public Form2()
{
InitializeComponent();
}
ArrayList inputValue = new ArrayList();
int avgValue = 0;
bool isFinish = false;
private void button1_Click(object sender, EventArgs e)
{
#region Init data
isFinish = false;
avgValue = 0;
inputValue.Clear();
listBox1.Items.Clear();
//assum you input valid number without space and in desc sorting order
string[] arrNumber = textBox1.Text.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
int numberOfBreak = 3;
int record = Convert.ToInt32(arrNumber[0]);//update the record with the maximum value of the array numbers
for (int i = 0; i < arrNumber.Length; i++)
{
inputValue.Add(Convert.ToInt32(arrNumber[i]));
}
foreach (object obj in inputValue)
{
avgValue += (int)obj;
}
avgValue = avgValue / numberOfBreak;
#endregion
int lastIndex = 0;
while (!isFinish)
{
int index = GetIndex(lastIndex);
string sResult = "";
for (int i = lastIndex; i <= index; i++)
{
sResult += inputValue[i].ToString() + "-";
}
listBox1.Items.Add(sResult);
if (index + 1 < inputValue.Count)
{
lastIndex = index + 1;
}
sResult = "";
}
}
private int GetIndex(int startIndex)
{
int index = -1;
int gap1 = Math.Abs(avgValue - (int)inputValue[startIndex]);
int tempSum = (int)inputValue[startIndex];
if (startIndex < inputValue.Count - 1)
{
int gap2 = 0;
while (gap1 > gap2 && !isFinish)
{
for (int i = startIndex + 1; i < inputValue.Count; i++)
{
tempSum += (int)inputValue[i];
gap2 = Math.Abs(avgValue - tempSum);
if (gap2 <= gap1)
{
gap1 = gap2;
gap2 = 0;
index = i;
if (startIndex <= inputValue.Count - 1)
{
startIndex += 1;
}
else
{
isFinish = true;
}
if (startIndex == inputValue.Count - 1)
{
index = startIndex;
isFinish = true;
}
break;
}
else
{
index = i - 1;
break;
}
}
}
}
else if (startIndex == inputValue.Count - 1)
{
index = startIndex;
isFinish = true;
}
else
{
isFinish = true;
}
return index;
}
}
}