from Google Code Jam - july/2008....
http://code.google.com/codejam
Problem
The urban legend goes that if you go to the Google homepage and search for "Google", the universe will implode. We have a secret to share... It is true! Please don't try it, or tell anyone. All right, maybe not. We are just kidding.
The same is not true for a universe far far away. In that universe, if you search on any search engine for that search engine's name, the universe does implode!
To combat this, people came up with an interesting solution. All queries are pooled together. They are passed to a central system that decides which query goes to which search engine. The central system sends a series of queries to one search engine, and can switch to another at any time. Queries must be processed in the order they're received. The central system must never send a query to a search engine whose name matches the query. In order to reduce costs, the number of switches should be minimized.
Your task is to tell us how many times the central system will have to switch between search engines, assuming that we program it optimally.
Input
The first line of the input file contains the number of cases, N. N test cases follow.
Each case starts with the number S -- the number of search engines. The next S lines each contain the name of a search engine. Each search engine name is no more than one hundred characters long and contains only uppercase letters, lowercase letters, spaces, and numbers. There will not be two search engines with the same name.
The following line contains a number Q -- the number of incoming queries. The next Q lines will each contain a query. Each query will be the name of a search engine in the case.
Output
For each input case, you should output:
Case #X: Ywhere X is the number of the test case and Y is the number of search engine switches. Do not count the initial choice of a search engine as a switch.
Limits
0 < N ≤ 20
Small dataset
2 ≤ S ≤ 10
0 ≤ Q ≤ 100
Large dataset
2 ≤ S ≤ 100
0 ≤ Q ≤ 1000
Sample
Input | Output |
2 | Case #1: 1 |
In the first case, one possible solution is to start by using Dont Ask, and switch to NSM after query number 8.
For the second case, you can use B9, and not need to make any switches.
SOLUTION
/**
*
*/
package codejam;
import java.io.File;
import java.io.FileInputStream;
import java.util.ArrayList;
/**
* @author Ricardo Alberto Harari - ricardo.harari@gmail.com
*
*/
public class SavingUniverse {
private static final String FILE_NAME = "/tmp/sample.txt";
/**
* pass the full location of the sample file as argument
* if you dont pass anything it will search at /tmp/sample.txt
*
* @param args
*/
public static void main(String[] args) {
String fname = args.length == 0 ? FILE_NAME : args[0];
try {
SavingUniverse o = new SavingUniverse();
o.start(fname);
} catch (Exception e) {
System.out.println("Oppps.");
System.out.println("An exception has been throw:" + e.getMessage());
e.printStackTrace();
}
}
private int n = 0; // # of cases
ArrayList
ArrayList
private void start(String fileName) throws Exception {
File f = new File(fileName); // sample file
int s = 0; // # of search engines
int q = 0; // # of queries
if (!f.exists() || !f.isFile()) throw new Exception("Sorry, " + fileName + " is not a valid file.");
FileInputStream fi = new FileInputStream(f);
int cint;
String tmp = new String();
int caseNum = 0;
while ((cint = fi.read()) > -1) {
char c = (char) cint;
if (c == '\r' || c == '\n') {
if (tmp.length() > 0) {
if (n == 0) {
try {
n = Integer.parseInt(tmp);
} catch (NumberFormatException nfe) {
// do nothing. the 1st line should not be in correct format
}
} else if (q >0) {
addQuery(tmp);
q--;
if (q == 0) {
process(caseNum);
s = 0;
}
} else if (s == 0) {
s = Integer.parseInt(tmp);
if (listEngines == null){
listEngines = new ArrayList
listQueries = new ArrayList
} else {
listEngines.clear();
listQueries.clear();
}
caseNum++;
} else if (s > 0) {
listEngines.add(new SEngineNode(tmp));
s--;
if (s == 0) s = -1;
} else if (s == -1) {
q = Integer.parseInt(tmp);
if (q == 0) { // no queries huh?
print(caseNum, 0);
s = 0;
}
}
tmp = "";
}
} else if (c != ' ') {
tmp += c;
}
}
if (n != 0 && q > 0) {
addQuery(tmp.toString());
q--;
if (q == 0) {
process(caseNum);
}
}
}
/**
*
*/
private void process(int caso) {
// check if the 1st node has value of 0
int counter = 0;
for (int i = 0; i <>
QueryNode qrynode = listQueries.get(i);
SEngineNode engine = qrynode.node;
ArrayList
int j = i + 1;
for (j = i; j <>
QueryNode qrynodenxt = listQueries.get(j);
removeEngine(farNodeList, qrynodenxt);
if (farNodeList.size() == 0) break;
}
if (farNodeList.size() == 0) {
counter++;
i = j - 1;
} else {
break;
}
}
print(caso, counter);
}
/**
* @param farNodeList
* @param qrynodenxt
*/
private void removeEngine(ArrayList
String s = qrynodenxt.query;
for (SEngineNode n : farNodeList) {
if (s.indexOf(n.engineName) > -1) {
farNodeList.remove(n);
break;
}
}
}
/**
* @return
*/
private ArrayList
ArrayList
for (SEngineNode node : listEngines) {
if (!node.engineName.equals(exceptNode.engineName)) ret.add(node);
}
return ret;
}
/**
* @param caso
* @param i
*/
private void print(int caso, int i) {
System.out.println("Case #" + caso + ": " + i);
}
/**
* @param string
*/
private void addQuery(String s) {
s = s.toUpperCase();
for (SEngineNode node : listEngines) {
if (s.indexOf(node.engineName) > -1) {
node.qtd++;
listQueries.add(new QueryNode(s, node));
break;
}
}
}
class QueryNode {
public QueryNode(String _query, SEngineNode _engine) {
query = _query;
node = _engine;
}
String query;
SEngineNode node;
}
class SEngineNode {
public SEngineNode(String _engineName) {
engineName = _engineName.toUpperCase().trim();
}
int qtd; // qtd that match this search engine
String engineName;
}
}
N