Only Duplicates

6_kyu/Only Duplicates/README.md

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+## Only Duplicates
+
+https://www.codewars.com/kata/5a1dc4baffe75f270200006b
+
+Given a string, remove any characters that are unique from the string.
+
+Example:
+
+input: "abccdefee"
+
+output: "cceee"

6_kyu/Only Duplicates/index.test.ts

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+import { onlyDuplicates } from "./index";
+
+describe("Tests", () => {
+    it("example", () => {
+        expect(onlyDuplicates("abccdefee")).toBe("cceee");
+        expect(onlyDuplicates("hello")).toBe("ll");
+        expect(onlyDuplicates("colloquial")).toBe("ollol");
+        expect(onlyDuplicates("foundersandcoders")).toBe("ondersndoders");
+    });
+});

6_kyu/Only Duplicates/index.ts

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+export function onlyDuplicates(str: string): string {
+    const array: string[] = str.split("");
+    const hashTable: { [key: string]: number } = {};
+
+    array.forEach((item) => {
+        if (hashTable[item]) {
+            hashTable[item]++;
+        } else {
+            hashTable[item] = 1;
+        }
+    });
+
+    const dublicates = array.filter((item) => hashTable[item] > 1);
+
+    return dublicates.join("");
+}

README.md

@@ -2,10 +2,10 @@
 
 ### Katas solved
 
-`Total`: 115 \
+`Total`: 116 \
 `8_kyu`: 92 \
 `7_kyu`: 15 \
-`6_kyu`: 8 \
+`6_kyu`: 9 \
 `5_kyu`: 0 \
 `4_kyu`: 0 \
 `3_kyu`: 0 \