(euler) - #8

euler/src/8 - Largest Product in a Series.ts

@@ -0,0 +1,36 @@
+const largestProduct = (number: bigint | number, adjacentDigits: number) => {
+    let cursorIndex = 0;
+    const selections: number[][] = [];
+
+    while (cursorIndex < number.toString().length) {
+        const characters = number.toString().split('');
+
+        // Select the next 13 numbers
+        const selection: number[] = [];
+
+        for (let i = 0; i < adjacentDigits; i++) {
+            selection.push(parseInt(characters[cursorIndex + i]));
+        }
+
+        if (!selection.includes(NaN)) selections.push(selection);
+
+        // Keep moving the cursor along
+        cursorIndex++;
+    }
+
+    // Work out the products
+    const products: number[] = [];
+
+    for (let i = 0; i < selections.length; i++) {
+        products.push(selections[i].reduce((a, b) => a * b));
+    }
+
+    // Return the largest product
+    return products.sort((a, b) => b - a)[0];
+};
+
+const number = BigInt(
+    '7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450'
+);
+
+console.log(largestProduct(number, 13));