findpos

Author: esadakman

5_kyu/findpos.md

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+## [Find Position in Sequence](https://www.codewars.com/kata/660323a44fe3e41cff41e4e9)
+
+- Given an increasing sequence where each element is an integer composed of digits from a given set `t`.
+
+- For example, if `t = { 1, 5 }`, the sequence would be: `1, 5, 11, 15, 51, 55, 111, 115, ...` 
+
+- Another example, `if t = { 4, 0, 2 }`, the sequence would be: `0, 2, 4, 20, 22, 24, 40, 42, ...`
+
+
+#### Task
+In this kata, you need to implement a function `findpos(n, t)` that receives a integer `n` and a table/set `t` representing the set of digits, and returns the position of `n` in the sequence.
+
+```js
+findpos(11, { 1 }) --> 2
+findpos(55, { 1, 5 }) --> 6
+findpos(42, { 4, 0, 2 }) --> 8
+findpos(1337, { 1, 3, 7 }) --> 54
+findpos(123456789, { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }) --> 123456790
+```
+#### Note
+- The integer `n` will always be in the sequence.
+#### Solution:
+
+```javascript
+function findpos(n, t) {
+    // Determine the modifier based on whether 0 is in the set
+    const modifier = t.has(0) ? 1 : 0;
+
+    // Create a map to store the order of each digit in the set
+    const orderMap = new Map([...t].sort((a, b) => a - b).map((number, index) => [number.toString(), index + 1 - modifier]));
+
+    // Calculate the position of n in the sequence
+    return n.toString()
+        .split("")
+        .reduceRight((acc, number, place, { length }) => {
+            return acc + orderMap.get(number) * t.size ** (length - place - 1);
+        }, 0 + modifier);
+}
+
+
+// Examples
+console.log(findpos(11, new Set([1]))); // Output: 2
+console.log(findpos(55, new Set([1, 5]))); // Output: 6
+
+```

README.md

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-    <td><a href="5 kyu "> </a></td>
+    <td><a href="https://github.com/esadakman/javaScript-coding-challenges/blob/master/5_kyu/findpos.md">findpos</a></td>
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