add 1273

fishercoder1534 · fishercoder1534 · commit 7bf365eb226f · 2020-02-11T08:59:54.000-08:00
diff --git a/README.md b/README.md
@@ -44,6 +44,7 @@ _If you like this project, please leave me a star._ &#9733;
 |1281|[Subtract the Product and Sum of Digits of an Integer](https://leetcode.com/problems/subtract-the-product-and-sum-of-digits-of-an-integer/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1281.java) |   |Easy||
 |1277|[Count Square Submatrices with All Ones](https://leetcode.com/problems/count-square-submatrices-with-all-ones/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1277.java) |   |Medium||
 |1275|[Find Winner on a Tic Tac Toe Game](https://leetcode.com/problems/find-winner-on-a-tic-tac-toe-game/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1275.java) |   |Easy|Array|
+|1273|[Delete Tree Nodes](https://leetcode.com/problems/delete-tree-nodes/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1273.java) |   |Medium|Dynamic Programming, DFS |
 |1271|[Hexspeak](https://leetcode.com/problems/hexspeak/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1271.java) |   |Easy||
 |1267|[Count Servers that Communicate](https://leetcode.com/problems/count-servers-that-communicate/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1267.java) |   |Medium||
 |1266|[Minimum Time Visiting All Points](https://leetcode.com/problems/minimum-time-visiting-all-points/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1266.java) |   |Easy||
diff --git a/src/main/java/com/fishercoder/solutions/_1273.java b/src/main/java/com/fishercoder/solutions/_1273.java
@@ -0,0 +1,55 @@
+package com.fishercoder.solutions;
+
+import java.util.Arrays;
+
+/**
+ * 1273. Delete Tree Nodes
+ *
+ * A tree rooted at node 0 is given as follows:
+ * The number of nodes is nodes;
+ * The value of the i-th node is value[i];
+ * The parent of the i-th node is parent[i].
+ * Remove every subtree whose sum of values of nodes is zero.
+ * After doing so, return the number of nodes remaining in the tree.
+ *
+ * Example 1:
+ *                      0 (1)
+ *                     /  \
+ *               (-2) 1    2 (4)
+ *                   /    / |   \
+ *              (0)3 (-2)4 (-1)5 6(-1)
+ *
+ * Input: nodes = 7, parent = [-1,0,0,1,2,2,2], value = [1,-2,4,0,-2,-1,-1]
+ * Output: 2
+ *
+ * Constraints:
+ * 1 <= nodes <= 10^4
+ * -10^5 <= value[i] <= 10^5
+ * parent.length == nodes
+ * parent[0] == -1 which indicates that 0 is the root.
+ * */
+public class _1273 {
+    public static class Solution1 {
+        public int deleteTreeNodes(int nodes, int[] parent, int[] value) {
+            int len = parent.length;
+            for (int i = len - 1; i > 0; ) {
+                int sum = 0;
+                int parentIndex = parent[i];
+                while (i > 0 && parent[i] == parentIndex) {
+                    sum += value[i--];
+                }
+                value[parentIndex] = value[parentIndex] + sum;
+            }
+            for (int i = 0; i < value.length; i++) {
+                if (value[i] == 0) {
+                    for (int j = 0; j < parent.length; j++) {
+                        if (parent[j] == i) {
+                            value[j] = 0;
+                        }
+                    }
+                }
+            }
+            return (int) Arrays.stream(value).filter(i -> i != 0).count();
+        }
+    }
+}
diff --git a/src/test/java/com/fishercoder/_1273Test.java b/src/test/java/com/fishercoder/_1273Test.java
@@ -0,0 +1,47 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._1273;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _1273Test {
+    private static _1273.Solution1 solution1;
+    private static int[] parent;
+    private static int[] value;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _1273.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        parent = new int[]{-1, 0, 0, 1, 2, 2, 2};
+        value = new int[]{1, -2, 4, 0, -2, -1, -1};
+        assertEquals(2, solution1.deleteTreeNodes(7, parent, value));
+    }
+
+    @Test
+    public void test2() {
+        parent = new int[]{-1, 0, 0, 1, 2, 2, 2};
+        value = new int[]{1, -2, 3, 0, -2, -1, 0};
+        assertEquals(2, solution1.deleteTreeNodes(7, parent, value));
+    }
+
+    @Test
+    public void test3() {
+        parent = new int[]{-1, 0, 0, 1, 2, 2, 2};
+        value = new int[]{1, -2, 4, 0, -2, -1, -2};
+        assertEquals(6, solution1.deleteTreeNodes(7, parent, value));
+    }
+
+    @Test
+    public void test4() {
+        parent = new int[]{-1, 0, 0, 1, 2, 2, 2};
+        value = new int[]{3, -2, 4, 0, -2, -1, -2};
+        assertEquals(0, solution1.deleteTreeNodes(7, parent, value));
+    }
+
+}
