challenge 167, task 1 in typescript

This code was written with/by github copilot

2 files changed, 82 insertions, 0 deletions

diff --git a/challenge-167/julien-fiegehenn/typescript/ch-1.ts b/challenge-167/julien-fiegehenn/typescript/ch-1.ts
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+// Write a script to find out first 10 circular primes having at least 3 digits (base 10).
+// A circular prime is a prime number with the property that the number generated at each 
+// intermediate step when cyclically permuting its (base 10) digits will also be prime.
+//
+// Output
+// 113, 197, 199, 337, 1193, 3779, 11939, 19937, 193939, 199933
+
+// this script was written by github copilot. it's not very efficient, but it works.
+
+// a function to check if a number is prime
+function isPrime(n: number): boolean {
+    if (n < 2) {
+        return false;
+    }
+    for (let i = 2; i < n; i++) {
+        if (n % i === 0) {
+            return false;
+        }
+    }
+    return true;
+}
+
+type Result = boolean | number[];
+// a function to check if a number is circular prime
+// returns false if it is not a circular prime
+// returns an array of the circular permutations if it is a circular prime
+function isCircularPrime(n: number): Result {
+    let circularPermutations: number[] = [];
+    let numberString: string = n.toString();
+    let numberStringLength: number = numberString.length;
+    for (let i = 0; i < numberStringLength; i++) {
+        let circularPermutation: string = numberString.slice(i) + numberString.slice(0, i);
+        let circularPermutationNumber: number = parseInt(circularPermutation);
+        if (!isPrime(circularPermutationNumber)) {
+            return false;
+        }
+        circularPermutations.push(circularPermutationNumber);
+    }
+    return circularPermutations;
+}
+// a function to find the first 10 circular primes 
+// the prime has to have three digits
+function findCircularPrimes(): number[] {
+    let circularPrimes: number[] = [];
+    let i = 0;
+
+    // store a dictionary of all permutations of the numbers
+    let circularPrimesDictionary: { [key: number]: boolean } = {};
+    while (circularPrimes.length < 10) {
+        // find out if the number is a circular prime and store the result
+        let result: Result = isCircularPrime(i);
+        // if the result is false, increment the number and continue
+        if (result === false) {
+            i++;
+            continue;
+        }
+        // if we have not seen the number before, add it to the circular primes array
+        if (circularPrimesDictionary[i] === undefined) {
+            // if the current number has at least 3 digits add it to the circular primes array
+            if (i.toString().length >= 3) {
+                circularPrimes.push(i);
+            }
+        }
+        
+        // store all the numbers from the result we have seen in the dictionary
+        for (let j = 0; j < (result as number[]).length; j++) {
+            circularPrimesDictionary[(result as number[])[j]] = true;
+        }
+        
+        i++;
+    } 
+    return circularPrimes;
+}
+
+console.log(findCircularPrimes());
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diff --git a/challenge-167/julien-fiegehenn/typescript/tsconfig.json b/challenge-167/julien-fiegehenn/typescript/tsconfig.json
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+{
+    "compilerOptions": {
+        "target": "ES6",
+        "module": "CommonJS",
+        "lib": ["ES6", "DOM"]
+    }
+}
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