Add problem 62

Author: juchanei

src/main/java/io/github/juchanei/leetcodeJava/UniquePaths.java

@@ -0,0 +1,66 @@
+package io.github.juchanei.leetcodeJava;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class UniquePaths {
+    private int m;
+    private int n;
+    private int[][] cache;
+
+    public int uniquePaths(int m, int n) {
+        this.m = m;
+        this.n = n;
+        this.cache = new int[m][n];
+
+        return find(0, 0);
+    }
+
+    private int find(int i, int j) {
+        if (i == m) return 0;
+        if (j == n) return 0;
+        if (i == m - 1 && j == n - 1) return 1;
+
+        if (0 < cache[i][j]) return cache[i][j];
+
+        return cache[i][j] = find(i + 1, j) + find(i, j + 1);
+    }
+
+    public static class UnitTest {
+
+        private UniquePaths up = new UniquePaths();
+
+        @Test
+        public void example1() {
+            int expected = 28;
+            int actual = up.uniquePaths(3, 7);
+
+            Assert.assertEquals(expected, actual);
+        }
+
+        @Test
+        public void example2() {
+            int expected = 3;
+            int actual = up.uniquePaths(3, 2);
+
+            Assert.assertEquals(expected, actual);
+        }
+
+        @Test
+        public void example3() {
+            int expected = 28;
+            int actual = up.uniquePaths(7, 3);
+
+            Assert.assertEquals(expected, actual);
+        }
+
+        @Test
+        public void example4() {
+            int expected = 6;
+            int actual = up.uniquePaths(3, 3);
+
+            Assert.assertEquals(expected, actual);
+        }
+    }
+
+}