712 leetcode solved

src/main/java/com/github/mstepan/leetcode/medium/MinimumAsciiDeleteSumForTwoStrings.java

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+package com.github.mstepan.leetcode.medium;
+
+import java.util.Objects;
+
+/**
+ * 712. Minimum ASCII Delete Sum for Two Strings
+ *
+ * <p>https://leetcode.com/problems/minimum-ascii-delete-sum-for-two-strings/description/
+ */
+public class MinimumAsciiDeleteSumForTwoStrings {
+
+    /**
+     * Solved using bottom-up dynamic programming approach.
+     *
+     * <p>time: O(N*K)
+     *
+     * <p>space: O(N*K) but can be reduced to O(min(N,K))
+     *
+     * <p>N = s1.length(), K = s2.length()
+     */
+    public static int minimumDeleteSum(String s1, String s2) {
+        Objects.requireNonNull(s1);
+        Objects.requireNonNull(s2);
+        final int rows = s1.length() + 1;
+        final int cols = s2.length() + 1;
+        int[][] opt = new int[rows][cols];
+
+        for (int row = 1; row < rows; ++row) {
+            opt[row][0] = opt[row - 1][0] + s1.charAt(row - 1);
+        }
+
+        for (int col = 1; col < cols; ++col) {
+            opt[0][col] = opt[0][col - 1] + s2.charAt(col - 1);
+        }
+
+        for (int row = 1; row < rows; ++row) {
+            for (int col = 1; col < cols; ++col) {
+
+                char c1 = s1.charAt(row - 1);
+                char c2 = s2.charAt(col - 1);
+
+                if (c1 == c2) {
+                    opt[row][col] = opt[row - 1][col - 1];
+                } else {
+                    opt[row][col] =
+                            Math.min(
+                                    opt[row - 1][col] + s1.charAt(row - 1),
+                                    opt[row][col - 1] + s2.charAt(col - 1));
+                }
+            }
+        }
+
+        return opt[rows - 1][cols - 1];
+    }
+}

src/test/java/com/github/mstepan/leetcode/medium/MinimumAsciiDeleteSumForTwoStringsTest.java

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+package com.github.mstepan.leetcode.medium;
+
+import static com.github.mstepan.leetcode.medium.MinimumAsciiDeleteSumForTwoStrings.minimumDeleteSum;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class MinimumAsciiDeleteSumForTwoStringsTest {
+
+    @Test
+    void case1() {
+        assertEquals(231, minimumDeleteSum("sea", "eat"));
+    }
+
+    @Test
+    void case2() {
+        assertEquals(403, minimumDeleteSum("delete", "leet"));
+    }
+}