Add solution directories for exercises

12_findTheOldest/solution/findTheOldest-solution.js

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+const findTheOldest = function (array) {
+    return array.reduce((oldest, currentPerson) => {
+        const oldestAge = getAge(oldest.yearOfBirth, oldest.yearOfDeath);
+        const currentAge = getAge(
+            currentPerson.yearOfBirth,
+            currentPerson.yearOfDeath
+        );
+        return oldestAge < currentAge ? currentPerson : oldest;
+    });
+};
+
+const getAge = function (birth, death) {
+    if (!death) {
+        death = new Date().getFullYear();
+    }
+    return death - birth;
+};
+
+module.exports = findTheOldest;

12_findTheOldest/solution/findTheOldest-solution.spec.js

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+const findTheOldest = require('./findTheOldest-solution');
+
+describe('findTheOldest', () => {
+    test('finds the oldest person!', () => {
+        const people = [
+            {
+                name: 'Carly',
+                yearOfBirth: 1942,
+                yearOfDeath: 1970,
+            },
+            {
+                name: 'Ray',
+                yearOfBirth: 1962,
+                yearOfDeath: 2011,
+            },
+            {
+                name: 'Jane',
+                yearOfBirth: 1912,
+                yearOfDeath: 1941,
+            },
+        ];
+        expect(findTheOldest(people).name).toBe('Ray');
+    });
+    test.skip('finds the oldest person if someone is still living', () => {
+        const people = [
+            {
+                name: 'Carly',
+                yearOfBirth: 2018,
+            },
+            {
+                name: 'Ray',
+                yearOfBirth: 1962,
+                yearOfDeath: 2011,
+            },
+            {
+                name: 'Jane',
+                yearOfBirth: 1912,
+                yearOfDeath: 1941,
+            },
+        ];
+        expect(findTheOldest(people).name).toBe('Ray');
+    });
+    test.skip('finds the oldest person if the OLDEST is still living', () => {
+        const people = [
+            {
+                name: 'Carly',
+                yearOfBirth: 1066,
+            },
+            {
+                name: 'Ray',
+                yearOfBirth: 1962,
+                yearOfDeath: 2011,
+            },
+            {
+                name: 'Jane',
+                yearOfBirth: 1912,
+                yearOfDeath: 1941,
+            },
+        ];
+        expect(findTheOldest(people).name).toBe('Carly');
+    });
+});