## Algorithm

Problem Name: Data Structures - Contacts

In this HackerRank in Data Structures - Contacts solutions

We're going to make our own Contacts application! The application must perform two types of operations:

1. add name, where name is a string denoting a contact name. This must store name as a new contact in the application.
2. find partial, where partial is a string denoting a partial name to search the application for. It must count the number of contacts starting with partial and print the count on a new line.

Given n sequential add and find operations, perform each operation in order.

Example
Operations are requested as follows:

find ed
find edw
find a

Three add operations include the names 'ed', 'eddie', and 'edward'. Next, find ed matches all 3 names. Note that it matches and counts the entire name 'ed'. Next, add 'edwina' and then find 'edw'. 2 names match: 'edward' and 'edwina'. In the final operation, there are 0 names that start with 'a'. Return the array [3,2,0]

Function Description

Complete the contacts function below.

contacts has the following parameters:

• string queries[n]: the operations to perform

Returns

• int[]: the results of each find operation

Input Format

The first line contains a single integer, n the number of operations to perform (the size of queries[])

Each of the following n lines contains a string queries[i]

Constraints

• 1 <= n <= 10**5
• 1 <= length of name <= 21
• 1 <= length of partial <= 21
• name and partial contain lowercase English letters only.
• The input does not have any duplicate name for the operation.

Sample Input

STDIN           Function
-----           --------
4               queries[] size n = 4
find hac
find hak

Sample Output

2
0

Explanation

1. Add a contact named hack.
2. Add a contact named hackerrank.
3. Find the number of contact names beginning with hac. Both name start with hac, add 2 to the return array.
4. Find the number of contact names beginning with hak. neither name starts with hak, add 0 to the return array.

## Code Examples

### #1 Code Example with C++ Programming

Code - C++ Programming

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
unordered_map < string,int> s;
int main(int argc, char** argv) {
int n; cin>>n;
while(n--){
string t,x; cin>>t>>x;
for(int i = 1; i <= x.length(); i++){
s[x.substr(0,i>]++;
}
}else{
cout << s[x] << endl;
}
}
return 0;
}
Copy The Code &

### #3 Code Example with Javascript Programming

Code - Javascript Programming

'use strict';

const fs = require('fs');

process.stdin.resume();
process.stdin.setEncoding('utf-8');

let inputString = '';
let currentLine = 0;

process.stdin.on('data', function(inputStdin) {
inputString += inputStdin;
});

process.stdin.on('end', function() {
inputString = inputString.split('\n');

main();
});

return inputString[currentLine++];
}

/*
* Complete the 'contacts' function below.
*
* The function is expected to return an INTEGER_ARRAY.
* The function accepts 2D_STRING_ARRAY queries as parameter.
*/

function contacts(queries) {
class TrieNode {
children = {}
isWord = false
count = 0 // -- we count while adding to be fast enough
}
class Trie {
root

constructor() {
this.root = new TrieNode()
}

insert(word) {
let node = this.root
let last = node
for (const l of word) {
if (!node.children[l]) {
node.children[l] = new TrieNode();
}
last = node
node = node.children[l]
}
last.isWord = true;
}
findNode(word) {
let node = this.root
let last = node
for (const l of word) {
if (!node.children[l])
return false
last = node
node = node.children[l]
}
return node
}
// count(node) { -- this is not fast enough
//     if (!node) return 0

//     let count = 0
//     if (node.isWord) count++
//     for (const l in node.children)
//         count += this.count(node.children[l])

//     return count
// }
}

let trie = new Trie()
let ret = []
for (const [command, word] of queries) {
trie.insert(word)
} else if (command === 'find') {
let node = trie.findNode(word)
//let count = trie.count(node) -- this is not fast enough
let count = node.count || 0
ret.push(count)
}
}
return ret
}

function main() {
const ws = fs.createWriteStream(process.env.OUTPUT_PATH);

let queries = Array(queriesRows);

for (let i = 0; i  <  queriesRows; i++) {
}

const result = contacts(queries);

ws.write(result.join('\n') + '\n');

ws.end();
}
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### #4 Code Example with Python Programming

Code - Python Programming

#!/bin/python3

import math
import os
import random
import re
import sys

#
# Complete the 'contacts' function below.
#
# The function is expected to return an INTEGER_ARRAY.
# The function accepts 2D_STRING_ARRAY queries as parameter.
#

def contacts(queries):
mpp, res = {}, []

for cmd,word in queries :
for i in range(len(word)) :
mpp[word[:i+1]] = mpp.get(word[:i+1],0)+1

else :
ans = 0
ans += mpp.get(word,0)
res.append(ans)

return res

if __name__ == '__main__':
fptr = open(os.environ['OUTPUT_PATH'], 'w')

queries_rows = int(input().strip())

queries = []

for _ in range(queries_rows):
queries.append(input().rstrip().split())

result = contacts(queries)

fptr.write('\n'.join(map(str, result)))
fptr.write('\n')

fptr.close()
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### #4 Code Example with Java Programming

Code - Java Programming

import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.function.*;
import java.util.regex.*;
import java.util.stream.*;
import static java.util.stream.Collectors.joining;
import static java.util.stream.Collectors.toList;

class Result {

/*
* Complete the 'contacts' function below.
*
* The function is expected to return an INTEGER_ARRAY.
* The function accepts 2D_STRING_ARRAY queries as parameter.
*/

public static List < Integer> contacts(List results = new ArrayList();
Map namePartials = new HashMap();

for (List < String> list : queries) {
String operation = list.get(0);
String text = list.get(1);

for (int i = 1; i  < = text.length(); ++i) {
String partial = text.substring(0, i);
Integer count = namePartials.get(partial);
if (count == null) {
count = 0;
}
count++;
namePartials.put(partial, count);
}
} else if (operation.equals("find")) {
Integer count = namePartials.get(text);
if (count == null) {
count = 0;
}
} else {
throw new RuntimeException("operation " + operation + " is not supported!");
}
}

return results;
}

}

public class Solution {
public static void main(String[] args) throws IOException {
BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

List < List();

IntStream.range(0, queriesRows).forEach(i -> {
try {
.collect(toList())
);
} catch (IOException ex) {
throw new RuntimeException(ex);
}
});

List < Integer> result = Result.contacts(queries);

bufferedWriter.write(
result.stream()
.map(Object::toString)
.collect(joining("\n"))
+ "\n"
);