�Solution to today's problem

src/main/java/com/github/spannm/leetcode/lc1/lc1200/Problem1220.java

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+package com.github.spannm.leetcode.lc1.lc1200;
+
+import com.github.spannm.leetcode.LeetcodeProblem;
+
+/**
+ * <a href="https://leetcode.com/problems/count-vowels-permutation/">1220. Count Vowels Permutation</a>.
+ */
+public class Problem1220 extends LeetcodeProblem {
+
+    public int countVowelPermutation(int _n) {
+        int mod = 1000_000_007;
+        long ca = 1;
+        long ce = 1;
+        long ci = 1;
+        long co = 1;
+        long cu = 1;
+        long a;
+        long e;
+        long i;
+        long o;
+        long u;
+
+        while (--_n > 0) {
+            a = (ce + ci + cu) % mod;
+            e = (ca + ci) % mod;
+            i = (ce + co) % mod;
+            o = ci;
+            u = (ci + co) % mod;
+
+            ca = a;
+            ce = e;
+            ci = i;
+            co = o;
+            cu = u;
+        }
+
+        return (int) ((ca + ce + ci + co + cu) % mod);
+    }
+
+}

src/test/java/com/github/spannm/leetcode/lc1/lc1200/Problem1220Test.java

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+package com.github.spannm.leetcode.lc1.lc1200;
+
+import com.github.spannm.leetcode.LeetcodeBaseTest;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+class Problem1220Test extends LeetcodeBaseTest {
+
+    @ParameterizedTest(name = "[{index}] {0} --> {1}")
+    @CsvSource(delimiter = ';', value = {
+        "1; 5",
+        "2; 10",
+        "5; 68"
+    })
+    void test(
+        int _n,
+        int _expectedResult) {
+
+        assertEquals(_expectedResult, new Problem1220().countVowelPermutation(_n));
+    }
+
+}