public RMQHelper(int[] inputArray)
{
this.inputArray = inputArray;
var cartesian = CartesianTreeNode.BuildCartesian(inputArray);
Earray = new int[inputArray.Length * 2 - 1];
Aarray = new int[inputArray.Length * 2 - 1];
Rarray = new int[inputArray.Length];
cartesian.WriteToArrays(Earray, 0, Aarray, Rarray);
innerHelper = new RMQPM1Helper(Aarray);
}
public static string FindLargestPalindrome(string s)
{
if (s.Length == 0)
{
return(string.Empty);
}
if (s.Length == 1)
{
return(s[0].ToString());
}
var rs = new string(s.Reverse().ToArray());
var ns = s + '\0' + rs;
var suffixTree = SuffixTreeNode.Build(ns);
var Earray = new int[(ns.Length + 2) * 4 - 1];
var Aarray = new int[(ns.Length + 2) * 4 - 1];
var Rarray = new int[ns.Length + 1];
suffixTree.WriteToArrays(Earray, 0, Aarray, Rarray);
var rmqHelper = new RMQPM1Helper(Aarray);
var lenMaxPalindrome = 0;
var midPalindrome = -1;
for (int i = 0; i < s.Length; i++)
{
var indL = Rarray[i + 1];
var indR = Rarray[ns.Length - i];
if (indL > indR)
{
int tmp = indL;
indL = indR;
indR = tmp;
}
int indexInE = rmqHelper.GetMinimum(indL, indR).Index;
var palindromeLength = Earray[indexInE];
if (palindromeLength > lenMaxPalindrome)
{
lenMaxPalindrome = palindromeLength;
midPalindrome = i + 1;
}
}
var startPalindrome = midPalindrome - lenMaxPalindrome;
var endPalindrome = startPalindrome + 2 * lenMaxPalindrome - 2;
var lenPalindrome = endPalindrome - startPalindrome + 1;
var r = s.Substring(startPalindrome, lenPalindrome);
return(r);
}
public static void BasicTest()
{
int[] arr = new[] { 0, 34, 65, 85, 23, 434, 43, 26, 786, 563, 2, 4, 46, 47, 74, 3, 13, 45, 85 };
arr = arr.Zip(arr.Skip(1)).Select(t => t.First > t.Second ? -1 : 1).ToArray();
for (int i = 1; i < arr.Length; i++)
{
arr[i] = arr[i] + arr[i - 1];
}
RMQPM1Helper helper = new RMQPM1Helper(arr);
int expected = arr.Skip(2).Take(5).Min();
int actual = helper.GetMinimum(2, 6).Value;
if (expected != actual)
{
throw new Exception("Basic test failed");
}
}
public static void LongTest(int maxTestArrayLength = 10000000, int testArraysCount = 2, int testsPerArray = 5)
{
Random rand = new Random();
for (int testArrayNr = 0; testArrayNr < testArraysCount; testArrayNr++)
{
int testArrayLength = rand.Next() % (maxTestArrayLength - 10) + 10;
int[] testArray = new int[testArrayLength];
for (int j = 1; j < testArrayLength; j++)
{
testArray[j] = rand.Next();
}
testArray = testArray.Zip(testArray.Skip(1)).Select(t => t.First > t.Second ? -1 : 1).ToArray();
for (int i = 1; i < testArray.Length; i++)
{
testArray[i] = testArray[i] + testArray[i - 1];
}
RMQPM1Helper finder = new RMQPM1Helper(testArray);
for (int test = 0; test < testsPerArray; test++)
{
int i = rand.Next() % (testArrayLength - 1);
int count = rand.Next() % (testArrayLength - i - 1) + 1;
int j = i + count - 1;
int expected = testArray.Skip(i).Take(count).Min();
int actual = finder.GetMinimum(i, j).Value;
var actualByIndex = testArray[finder.GetMinimum(i, j).Index];
if (actual != expected || actualByIndex != expected)
{
throw new Exception("Long test failed");
}
}
}
}
