You are given an input string.
For each symbol in the string if it’s the first character occurrence, replace it with a ‘1’, else replace it with the amount of times you’ve already seen it.
Examples:
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input = "Hello, World!"
result = "1112111121311"
input = "aaaaaaaaaaaa"
result = "123456789101112"
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There might be some non-ascii characters in the string.
Note: there will be no int domain overflow (character occurrences will be less than 2 billion).
The solution in Java code
Option 1:
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import java.util.*;
public class StringNumericals {
public static String numericals(String s) {
StringBuilder ret = new StringBuilder();
Map<String,Integer> map = new HashMap<>();
for (String c : s.split("")) {
map.put(c, 1 + map.getOrDefault(c,0));
ret.append(map.get(c));
}
return ret.toString();
}
}
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Option 2:
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public class StringNumericals {
public static String numericals(String s) {
StringBuilder output = new StringBuilder();
int readCharacters[] = new int[2024];
int index;
for (int i=0; i<s.length(); i++){
index=(int)s.charAt(i);
readCharacters[index]++;
output.append(readCharacters[index]);
}
return output.toString();
}
}
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Option 3:
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public class StringNumericals {
public static String numericals(String s) {
int[] f = new int[1032];
return s.chars()
.map(i -> ++f[i])
.collect(StringBuilder::new, StringBuilder::append, StringBuilder::append)
.toString();
}
}
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Test cases to validate our solution
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import org.junit.Test;
import static org.junit.Assert.assertEquals;
import org.junit.runners.JUnit4;
import java.util.*;
public class SolutionTest {
@Test
public void basicTest0() {
assertEquals("123456789101112", StringNumericals.numericals("aaaaaaaaaaaa"));
}
@Test
public void basicTest1() {
assertEquals("1112111121311", StringNumericals.numericals("Hello, World!"));
}
@Test
public void basicTest3() {
assertEquals("11121122342", StringNumericals.numericals("hello hello"));
}
@Test
public void fixedTest1() {
assertEquals("12345", StringNumericals.numericals("11111"));
}
@Test
public void fixedTest2() {
assertEquals("1111112121111111113212311414121151151262267232231",
StringNumericals.numericals("hope you 123456789 expected numbers in the string"));
}
@Test
public void fixedTest3() {
assertEquals("11111112221221132112411115312263237221234482193101343525441123124155131",
StringNumericals.numericals("In this string, I'll make sure the amounts of a character go over 9"));
}
public static String answer(String s) {
StringBuilder ret = new StringBuilder();
Map<String,Integer> map = new HashMap<>();
for (String c : s.split("")) {
map.put(c, 1 + map.getOrDefault(c,0));
ret.append(map.get(c));
}
return ret.toString();
}
@Test
public void randomTests() {
for (int i = 0; i < 100; i++) {
int N = (int)(Math.random()*10 + 200);
char[] r = new char[N];
for (int j = 0; j < N; j++) {
char c = (char)(Math.random()*1000 + 32);
r[j] = c;
}
String s = String.valueOf(r);
String expected = answer(s), actual = StringNumericals.numericals(s);
assertEquals(expected,actual);
}
}
@Test
public void randomTestsBiggerStrings() {
for (int i = 0; i < 100; i++) {
int N = (int)(Math.random()*100 + 100000);
char[] r = new char[N];
for (int j = 0; j < N; j++) {
char c = (char)(Math.random()*200 + 32);
r[j] = c;
}
String s = String.valueOf(r);
String expected = answer(s), actual = StringNumericals.numericals(s);
assertEquals(expected,actual);
}
}
}
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