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Construct the Suffix Array of a Long String using LCP Array
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‎Algorithms on String/Algortihmic challenges of String Processing/LCPpatternMatching.cs

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using System;
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using System.Collections;
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using System.Collections.Generic;
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using System.Linq;
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namespace AlgorithmsOnStrin_W4Q2
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{
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public class W4Q2
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{
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public static void Main()
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{
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string text = Console.ReadLine();
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long[] order = SortCharacters(text);
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long[] _class = ComputeCharClasses(text, order);
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long L = 1;
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while (L < text.Length)
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{
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order = SortDoubled(text, L, ref order, ref _class);
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_class = UpdateClasses(ref order, ref _class, L);
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L *= 2;
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}
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for (int i = 0; i < order.Length; i++)
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{
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Console.Write(order[i] + " ");
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}
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}
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public static long[] SortCharacters(string S)
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{
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int n = S.Length;
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long[] order = new long[n];
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long[] count = new long[256];
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for (int i = 0; i < n; i++) count[S[i]]++;
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for (int j = 1; j < 256; j++) count[j] += count[j - 1];
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for (int i = n - 1; i >= 0; i--)
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{
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char c = S[i];
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count[c]--;
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order[count[c]] = i;
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}
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return order;
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}
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public static long[] ComputeCharClasses(string S, long[] order)
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{
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int n = S.Length;
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long[] _classes = new long[n];
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_classes[order[0]] = 0;
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for (int i = 1; i < n; i++)
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{
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if (S[(int)order[i]] != S[(int)order[i - 1]]) _classes[order[i]] = _classes[order[i - 1]] + 1;
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else _classes[order[i]] = _classes[order[i - 1]];
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}
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return _classes;
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}
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public static long[] SortDoubled(string S, long L, ref long[] order, ref long[] _class)
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{
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int n = S.Length;
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long[] count = new long[n];
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long[] newOrder = new long[n];
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for (int i = 0; i < n; i++) count[_class[i]]++;
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for (int i = 1; i < n; i++) count[i] += count[i - 1];
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for (int i = n - 1; i >= 0; i--)
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{
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long start = (order[i] - L + n) % n;
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long cl = _class[(int)start];
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count[cl]--;
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newOrder[count[cl]] = start;
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}
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return newOrder;
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}
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public static long[] UpdateClasses(ref long[] newOrder, ref long[] _class, long L)
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{
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int n = newOrder.Length;
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long[] newClass = new long[n];
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newClass[newOrder[0]] = 0;
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for (int i = 1; i < n; i++)
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{
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long cur = newOrder[i];
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long prev = newOrder[i - 1];
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long mid = (cur + L) % n;
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long midPrev = (prev + L) % n;
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if (_class[cur] != _class[prev] || _class[mid] != _class[midPrev]) newClass[cur] = newClass[prev] + 1;
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else newClass[cur] = newClass[prev];
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}
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return newClass;
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}
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}
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}

‎Algorithms on String/Algortihmic challenges of String Processing/constructSAbyLCP.cs

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using System;
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using System.Collections;
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using System.Collections.Generic;
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using System.Linq;
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namespace AlgorithmsOnStrin_W4Q2
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{
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public class W4Q2
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{
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public static void Main()
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{
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string text = Console.ReadLine();
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long[] order = SortCharacters(text);
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long[] _class = ComputeCharClasses(text, order);
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long L = 1;
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while (L < text.Length)
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{
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order = SortDoubled(text, L, ref order, ref _class);
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_class = UpdateClasses(ref order, ref _class, L);
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L *= 2;
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}
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for (int i = 0; i < order.Length; i++)
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{
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Console.Write(order[i] + " ");
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}
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}
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public static long[] SortCharacters(string S)
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{
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int n = S.Length;
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long[] order = new long[n];
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long[] count = new long[256];
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for (int i = 0; i < n; i++) count[S[i]]++;
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for (int j = 1; j < 256; j++) count[j] += count[j - 1];
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for (int i = n - 1; i >= 0; i--)
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{
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char c = S[i];
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count[c]--;
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order[count[c]] = i;
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}
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return order;
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}
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public static long[] ComputeCharClasses(string S, long[] order)
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{
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int n = S.Length;
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long[] _classes = new long[n];
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_classes[order[0]] = 0;
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for (int i = 1; i < n; i++)
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{
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if (S[(int)order[i]] != S[(int)order[i - 1]]) _classes[order[i]] = _classes[order[i - 1]] + 1;
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else _classes[order[i]] = _classes[order[i - 1]];
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}
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return _classes;
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}
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public static long[] SortDoubled(string S, long L, ref long[] order, ref long[] _class)
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{
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int n = S.Length;
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long[] count = new long[n];
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long[] newOrder = new long[n];
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for (int i = 0; i < n; i++) count[_class[i]]++;
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for (int i = 1; i < n; i++) count[i] += count[i - 1];
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for (int i = n - 1; i >= 0; i--)
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{
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long start = (order[i] - L + n) % n;
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long cl = _class[(int)start];
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count[cl]--;
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newOrder[count[cl]] = start;
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}
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return newOrder;
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}
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public static long[] UpdateClasses(ref long[] newOrder, ref long[] _class, long L)
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{
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int n = newOrder.Length;
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long[] newClass = new long[n];
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newClass[newOrder[0]] = 0;
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for (int i = 1; i < n; i++)
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{
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long cur = newOrder[i];
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long prev = newOrder[i - 1];
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long mid = (cur + L) % n;
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long midPrev = (prev + L) % n;
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if (_class[cur] != _class[prev] || _class[mid] != _class[midPrev]) newClass[cur] = newClass[prev] + 1;
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else newClass[cur] = newClass[prev];
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}
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return newClass;
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}
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}
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}

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