feat: kata/how-many-streets

docs/README.md

@@ -1,7 +1,7 @@
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@@ -25,7 +25,7 @@ slug.
 
 | [1 kyu](/kata/1-kyu/index.md) | [2 kyu](/kata/2-kyu/index.md) | [3 kyu](/kata/3-kyu/index.md) | [4 kyu](/kata/4-kyu/index.md) | [5 kyu](/kata/5-kyu/index.md) | [6 kyu](/kata/6-kyu/index.md) | [7 kyu](/kata/7-kyu/index.md) | [8 kyu](/kata/8-kyu/index.md) | [beta](/kata/beta/index.md) | [retired](/kata/retired/index.md) |
 |:-----------------------------:|:-----------------------------:|:-----------------------------:|:-----------------------------:|:-----------------------------:|:-----------------------------:|:-----------------------------:|:-----------------------------:|:---------------------------:|:---------------------------------:|
-| 0 | 1 | 2 | 26 | 48 | 431 | 588 | 218 | 56 | 79 |
+| 0 | 1 | 2 | 26 | 48 | 431 | 590 | 218 | 56 | 79 |
 
 **Note:** The source code is written in Java 17 and may use language features that are incompatible
 with Java 8, 11.

kata/7-kyu/how-many-streets/README.md

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+# [How Many Streets?](https://www.codewars.com/kata/how-many-streets "https://www.codewars.com/kata/66fc9ca2e6d1d0e9cc2e4a4c")
+
+The longest street in the world, MAX_STREET, is crossed by many other streets and driven by many drivers. Determine how many streets each
+driver crosses.
+
+#### Inputs
+
+1. A list (or array, depending on language) of streets that intersect MAX_STREET.
+2. A list (or array, depending on language) of drivers. Each driver is represented by a pair of streets. The first element of the pair is
+   the street where they enter MAX_STREET; the second is the street they exit. The driver crosses all the streets between those two streets.
+
+#### Output
+
+A list (or array, depending on language) showing how many streets each driver crosses.
+
+#### Example
+
+```
+count_streets(
+  ["first", "second", "third", "fourth", "fifth", "sixth", "seventh"],
+  [("first", "second"), ("second", "seventh"), ("sixth", "fourth")]
+)
+```
+
+should return `[0,4,1]`.
+
+#### Details:
+
+1. Each street name is a non-empty word of no more than 10 letters. There are no duplicate street names.
+2. The entry and exit streets for each driver are distinct. They are guaranteed to come from the list of streets.
+3. The number of streets `n` satisfies <code>2 ≤ n ≤ 10<sup>5</sup></code>. The number of drivers `d`
+   satisfies <code>1 ≤ d ≤ 10<sup>5</sup>.</code> So efficiency is important.

kata/7-kyu/how-many-streets/main/HowManyStreets.java

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+import static java.util.Arrays.stream;
+import static java.util.stream.Collectors.toMap;
+import static java.util.stream.IntStream.range;
+
+interface HowManyStreets {
+  static int[] countStreets(String[] streets, String[][] drivers) {
+    var map = range(0, streets.length).boxed().collect(toMap(i -> streets[i], i -> i));
+    return stream(drivers).mapToInt(d -> Math.abs(map.get(d[1]) - map.get(d[0])) - 1).toArray();
+  }
+}

kata/7-kyu/how-many-streets/test/HowManyStreetsTest.java

@@ -0,0 +1,24 @@
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+import org.junit.jupiter.api.Test;
+
+class HowManyStreetsTest {
+  @Test
+  void sample() {
+    assertArrayEquals(new int[]{0, 4, 1}, HowManyStreets.countStreets(
+        new String[]{"first", "second", "third", "fourth", "fifth", "sixth", "seven"},
+        new String[][]{{"first", "second"}, {"second", "seven"}, {"sixth", "fourth"}}));
+
+    assertArrayEquals(new int[]{8, 6, 0, 4, 1, 7, 0, 8, 3, 2, 5}, HowManyStreets.countStreets(
+        new String[]{"a", "b", "c", "d", "e", "f", "g", "h", "i", "j"},
+        new String[][]{{"j", "a"}, {"b", "i"}, {"c", "d"}, {"e", "j"}, {"i", "g"}, {"a", "i"}, {"f", "e"}, {"a", "j"}, {"e", "a"}, {"e", "h"}, {"h", "b"}}));
+
+    assertArrayEquals(new int[]{0}, HowManyStreets.countStreets(
+        new String[]{"first", "second"},
+        new String[][]{{"second", "first"}}));
+
+    assertArrayEquals(new int[]{0, 1, 0, 0, 1}, HowManyStreets.countStreets(
+        new String[]{"Drive", "DrivE", "carefully"},
+        new String[][]{{"Drive", "DrivE"}, {"Drive", "carefully"}, {"DrivE", "Drive"}, {"Drive", "DrivE"}, {"carefully", "Drive"}}));
+  }
+}

kata/7-kyu/index.md

@@ -256,6 +256,7 @@
 - [How many arguments](how-many-arguments)
 - [How many consecutive numbers are needed?](how-many-consecutive-numbers-are-needed)
 - [How many days are we represented in a foreign country?](how-many-days-are-we-represented-in-a-foreign-country)
+- [How Many Streets?](how-many-streets)
 - [How many urinals are free?](how-many-urinals-are-free)
 - [Hungarian Vowel Harmony (easy)](hungarian-vowel-harmony-easy)
 - [Hëävÿ Mëtäl Ümläüts](heavy-metal-umlauts)