feat : new dp algo added UniqueSubsequenceCount.java

src/main/java/com/thealgorithms/dynamicprogramming/UniqueSubsequencesCount.java

@@ -0,0 +1,53 @@
+package com.thealgorithms.dynamicprogramming;
+
+// Program to find the number of Subsequences can be produced from a string
+
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Set;
+
+// Author -> https://github.com/Tuhinm2002
+
+public final class UniqueSubsequencesCount {
+
+    private UniqueSubsequencesCount() {
+        throw new UnsupportedOperationException("Utility class");
+    }
+
+    public static int subseqCount(String str) {
+
+        int[] dp = new int[str.length() + 1];
+        Arrays.fill(dp, -1);
+
+        return recursiveCall(str, 0, dp);
+    }
+
+    public static int recursiveCall(String st, int idx, int[] dp) {
+
+        if (idx >= st.length()) {
+            return 0;
+        }
+
+        if (dp[idx] != -1) {
+            return dp[idx];
+        }
+
+        Set<Character> set = new HashSet<>();
+
+        int res = 0;
+
+        for (int j = idx; j < st.length(); j++) {
+
+            if (set.contains(st.charAt(j))) {
+                continue;
+            }
+
+            set.add(st.charAt(j));
+
+            res = 1 + recursiveCall(st, j + 1, dp) + res;
+        }
+
+        dp[idx] = res;
+        return dp[idx];
+    }
+}

src/test/java/com/thealgorithms/dynamicprogramming/UniqueSubsequencesCountTest.java

@@ -0,0 +1,29 @@
+package com.thealgorithms.dynamicprogramming;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public final class UniqueSubsequencesCountTest {
+
+    @Test
+    void subseqCountTestOne() {
+        String s = "abc";
+
+        assertEquals(7, UniqueSubsequencesCount.subseqCount(s));
+    }
+
+    @Test
+    void subseqCountTestTwo() {
+        String s = "abcdashgdhas";
+
+        assertEquals(3592, UniqueSubsequencesCount.subseqCount(s));
+    }
+
+    @Test
+    void subseqCountTestThree() {
+        String s = "aaaaa";
+
+        assertEquals(5, UniqueSubsequencesCount.subseqCount(s));
+    }
+}