Sample Problem Statements

Sample Problem Statements

Here are a couple of examples of the types of problems you can expect from a TopCoder competition. Once you become a TopCoder member, you can view all of the problems that TopCoder has ever used in the statistics section of our web site. If you're looking to practice, you'll find that after each TopCoder competition the problem sets that were used will be added as "practice rooms" in the TopCoder competition Arena. The TopCoder practice rooms are a great place to test your skills without the pressure of live competition and at the same time, get a feel for the competition environment. During an event you are presented with mulitple problems (usually 3) of increasing difficulty.

Example Level 1 Problem Statement
(From SRM 303)

Problem Statement
In the English language, the plural form of a noun is created according to many difficult rules, but for the most part, a noun can be transformed into its plural form using four simple rules. These rules are:

1. If the word ends in 's', 'z', 'x', 'ch' or 'sh', add 'es' to the end of the word;
2. If the word ends in 'ay', 'ey', 'iy', 'oy' or 'uy', add 's' to the end of the word;
3. If the word ends in 'y', but doesn't satisfy the previous rule, replace the trailing 'y' with 'ies';
4. In all other cases, just add 's' to the end of the word.

Class:            NounReform
Method:           makePlural
Parameters:       String[]
Returns:          String[]
Method signature: String[] makePlural(String[] nouns)
(be sure your methodis public)

public class NounReform {
  public String[] makePlural(String[] nouns) {
    String[] ret = new String[nouns.length];
    int count = 0;
    for(String s : nouns) {
      if(s.endsWith("s") || s.endsWith("z") || s.endsWith("x") || s.endsWith("ch") || s.endsWith("sh")) {
        //Rule 1
        ret[count++] = s + "es";
      } else if(s.endsWith("ay") || s.endsWith("ey") || s.endsWith("iy") || s.endsWith("oy") || s.endsWith("uy")) {
        //Rule 2
        ret[count++] = s + "s";
      } else if(s.endsWith("y")) {
        //Rule 3
        ret[count++] = s.substring(0, s.length() -1) + "ies";
      } else {
        ret[count++] = s + "s";
      }
    }
    return ret;
  }
}

public class NounReform {
  public string[] makePlural(string[] nouns) {
    string[] ret = new string[nouns.Length];
    int count = 0;
    foreach(string s in nouns) {
      if(s.EndsWith("s") || s.EndsWith("z") || s.EndsWith("x") || s.EndsWith("ch") || s.EndsWith("sh")) {
        //Rule 1
        ret[count++] = s + "es";
      } else if(s.EndsWith("ay") || s.EndsWith("ey") || s.EndsWith("iy") || s.EndsWith("oy") || s.EndsWith("uy")) {
        //Rule 2
        ret[count++] = s + "s";
      } else if(s.EndsWith("y")) {
        //Rule 3
        ret[count++] = s.Substring(0, s.Length -1) + "ies";
      } else {
        ret[count++] = s + "s";
      }
    }
    return ret;
  }
}

#include<vector>
#include<string>

using namespace std;

class NounReform {
  int endsWith(string a, string b) {
    if(a.size() < b.size())
      return 0;
    for(int i = 0; i < b.size(); i++) {
      if(a[a.size()-i-1] != b[b.size()-i-1])
        return 0;
    }
    return 1;
  }

  public:
    vector<string> makePlural(vector<string> nouns) {
      vector<string> ret;
      for(int i = 0; i < nouns.size(); i++) {
        if(endsWith(nouns[i],"s") || endsWith(nouns[i],"z") || endsWith(nouns[i],"x") || endsWith(nouns[i],"ch") || endsWith(nouns[i],"sh")) {
          //Rule 1
          ret.push_back(nouns[i] + "es");
        } else if(endsWith(nouns[i],"ay") || endsWith(nouns[i],"ey") || endsWith(nouns[i],"iy") || endsWith(nouns[i],"oy") || endsWith(nouns[i],"uy")) {
          //Rule 2
          ret.push_back(nouns[i] + "s");
        } else if(endsWith(nouns[i],"y")) {
          //Rule 3
          ret.push_back(nouns[i].substr(0, nouns[i].size() -1) + "ies");
        } else {
          ret.push_back(nouns[i] + "s");
        }
      }
      return ret;
  }
};

Public Class NounReform
  Public Function makePlural(nouns as String()) as String() 
    Dim ret as String()
    Redim ret(nouns.Length - 1)

    For i as Integer = 0 To nouns.Length - 1
      If nouns(i).EndsWith("s") Or nouns(i).EndsWith("z") Or nouns(i).EndsWith("x") Or nouns(i).EndsWith("ch") Or nouns(i).EndsWith("sh") Then
        'Rule 1
        ret(i) = nouns(i) + "es"
      Else If nouns(i).EndsWith("ay") Or nouns(i).EndsWith("ey") Or nouns(i).EndsWith("iy") Or nouns(i).EndsWith("oy") Or nouns(i).EndsWith("uy") Then
        'Rule 2
        ret(i) = nouns(i) + "s"
      Else If nouns(i).EndsWith("y") Then
        'Rule 3
        ret(i) = nouns(i).Substring(0, nouns(i).Length -1) + "ies"
      Else
        ret(i) = nouns(i) + "s"
      End If
    Next
    Return ret
  End Function
End Class

Old format stats:  |  New format stats:
John-DH            |  John-DH,RP,SP         
Jack-SP            |  Jack-SP               
Sam-OF             |  Sam-OF                
John-SP            |  John-SP,DH,RP         
John-RP            |  John-RP,DH,SP

Class:            XBallGame
Method:           newStatistics
Parameters:       String[]
Returns:          String[]
Method signature: String[] newStatistics(String[] placeboard)
(be sure your methodis public)

import java.util.ArrayList;
import java.util.Collections;

public class XBallGame {
  public String[] newStatistics(String[] placeboard) {
    String[] ret = new String[placeboard.length];
    for(int i = 0; i < ret.length; i++) {
      ret[i] = placeboard[i];

      ArrayList positions = new ArrayList();

      for(int j = 0; j < placeboard.length; j++) {
        if(i == j) continue;
        if(ret[i].substring(0,ret[i].indexOf("-")).equals(placeboard[j].substring(0,placeboard[j].indexOf("-")))) {
          //same person
          positions.add(placeboard[j].substring(placeboard[j].indexOf("-")+1));
        }
      }

      Collections.sort(positions);
      for(String s : positions) {
        ret[i] = ret[i] + "," + s;
      }
    }
    return ret;
  }
}

using System.Collections.Generic;

public class XBallGame {
  public string[] newStatistics(string[] placeboard) {
    string[] ret = new string[placeboard.Length];
    for(int i = 0; i < ret.Length; i++) {
      ret[i] = placeboard[i];

      List positions = new List();

      for(int j = 0; j < placeboard.Length; j++) {
        if(i == j) continue;
        if(ret[i].Substring(0,ret[i].IndexOf("-")) == placeboard[j].Substring(0,placeboard[j].IndexOf("-"))) {
          //same person
          positions.Add(placeboard[j].Substring(placeboard[j].IndexOf("-")+1));
        }
      }

      positions.Sort();

      foreach(string s in positions) {
        ret[i] = ret[i] + "," + s;
      }
    }
    return ret;
  }
}

#include<vector>
#include<string>

using namespace std;

class XBallGame {
  public:
    vector<string> newStatistics(vector<string> placeboard) {
      vector<string> ret(placeboard.size());
      for(int i = 0; i < ret.size(); i++) {
        ret[i] = placeboard[i];

        vector<string> positions;

        for(int j = 0; j < placeboard.size(); j++) {
          if(i == j) continue;
          if(ret[i].substr(0,ret[i].find("-")) == placeboard[j].substr(0,placeboard[j].find("-"))) {
            //same person
            positions.push_back(placeboard[j].substr(placeboard[j].find("-")+1));
          }
        }

        sort(positions.begin(), positions.end());

        for(int k = 0; k < positions.size(); k++) {
          ret[i] = ret[i] + "," + positions[k];
        }
      }
      return ret;
    }
};

Imports System.Collections.Generic

Public Class XBallGame 
  Public Function newStatistics(placeboard as String()) as String()
    Dim ret as String()
    Redim ret(placeboard.Length-1)

    For i as Integer = 0 To ret.Length - 1
      ret(i) = placeboard(i)

      Dim positions as New List(Of String) 

      For j as Integer = 0 To placeboard.Length -1 
        If Not i = j Then
          If ret(i).Substring(0,ret(i).IndexOf("-")) = placeboard(j).Substring(0,placeboard(j).IndexOf("-")) Then
            'same person
            positions.Add(placeboard(j).Substring(placeboard(j).IndexOf("-")+1))
          End If
        End If
      Next

      positions.Sort()

      For k as Integer = 0 To positions.Count -1
        ret(i) = ret(i) + "," + positions(k)
      Next
    Next
    Return ret
  End Function
End Class