Added task 3754

src/main/java/g3701_3800/s3754_concatenate_non_zero_digits_and_multiply_by_sum_i/Solution.java

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+package g3701_3800.s3754_concatenate_non_zero_digits_and_multiply_by_sum_i;
+
+// #Easy #Math #Mid_Level #Weekly_Contest_477
+// #2026_04_25_Time_1_ms_(100.00%)_Space_42.50_MB_(73.85%)
+
+public class Solution {
+    public long sumAndMultiply(int n) {
+        int newNum = 0;
+        int y = Math.abs(n);
+        while (y > 0) {
+            int rem = y % 10;
+            if (rem != 0) {
+                newNum = newNum * 10 + rem;
+            }
+            y /= 10;
+        }
+        int temp = 0;
+        while (newNum > 0) {
+            int rem = newNum % 10;
+            temp = temp * 10 + rem;
+            newNum /= 10;
+        }
+        int x = temp;
+        long sum = 0;
+        while (temp > 0) {
+            int rem = temp % 10;
+            sum += rem;
+            temp /= 10;
+        }
+        return sum * x;
+    }
+}

src/main/java/g3701_3800/s3754_concatenate_non_zero_digits_and_multiply_by_sum_i/readme.md

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+3754\. Concatenate Non-Zero Digits and Multiply by Sum I
+
+Easy
+
+You are given an integer `n`.
+
+Form a new integer `x` by concatenating all the **non-zero digits** of `n` in their original order. If there are no **non-zero** digits, `x = 0`.
+
+Let `sum` be the **sum of digits** in `x`.
+
+Return an integer representing the value of `x * sum`.
+
+**Example 1:**
+
+**Input:** n = 10203004
+
+**Output:** 12340
+
+**Explanation:**
+
+*   The non-zero digits are 1, 2, 3, and 4. Thus, `x = 1234`.
+*   The sum of digits is `sum = 1 + 2 + 3 + 4 = 10`.
+*   Therefore, the answer is `x * sum = 1234 * 10 = 12340`.
+
+**Example 2:**
+
+**Input:** n = 1000
+
+**Output:** 1
+
+**Explanation:**
+
+*   The non-zero digit is 1, so `x = 1` and `sum = 1`.
+*   Therefore, the answer is `x * sum = 1 * 1 = 1`.
+
+**Constraints:**
+
+*   <code>0 <= n <= 10<sup>9</sup></code>

src/test/java/g3701_3800/s3754_concatenate_non_zero_digits_and_multiply_by_sum_i/SolutionTest.java

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+package g3701_3800.s3754_concatenate_non_zero_digits_and_multiply_by_sum_i;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+import org.junit.jupiter.api.Test;
+
+class SolutionTest {
+    @Test
+    void sumAndMultiply() {
+        assertThat(new Solution().sumAndMultiply(10203004), equalTo(12340L));
+    }
+
+    @Test
+    void sumAndMultiply2() {
+        assertThat(new Solution().sumAndMultiply(1000), equalTo(1L));
+    }
+}