SegmentTree perfection.

liusishan · Feb 27, 2019 · 26310dc · 26310dc
1 parent a38d380
commit 26310dc
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Showing 2 changed files with 26 additions and 1 deletion.
diff --git a/09-Segment-Tree/01-Segment-Tree-Basics/src/Main.java b/09-Segment-Tree/01-Segment-Tree-Basics/src/Main.java
@@ -6,5 +6,13 @@
 public class Main {
  public static void main(String[] args) {
 
+ Integer[] nums = {-2, 0, 3, -5, 2 - 1};
+ SegmentTree<Integer> segmentTree = new SegmentTree<>(nums, new Merger<Integer>() {
+ @Override
+ public Integer merge(Integer a, Integer b) {
+ return a + b;
+ }
+ });
+ System.out.println(segmentTree);
  }
 }
diff --git a/09-Segment-Tree/01-Segment-Tree-Basics/src/SegmentTree.java b/09-Segment-Tree/01-Segment-Tree-Basics/src/SegmentTree.java
@@ -18,7 +18,7 @@ public SegmentTree(E[] arr, Merger<E> merger) {
  data[i] = arr[i];
 
  tree = (E[]) new Object[4 * arr.length];
- buildSegmentTree(0, 0, data.length);
+ buildSegmentTree(0, 0, data.length - 1);
  }
 
  // 在treeIndex的位置创建表示区间[l...r]的线段树
@@ -60,4 +60,21 @@ private int rightChild(int index) {
  return 2 * index + 2;
  }
 
+ @Override
+ public String toString() {
+ StringBuilder res = new StringBuilder();
+ res.append('[');
+ for (int i = 0; i < tree.length; i++) {
+ if (tree[i] != null)
+ res.append(tree[i]);
+ else
+ res.append("null");
+
+ if (i != tree.length - 1)
+ res.append(", ");
+ }
+ res.append(']');
+ return res.toString();
+ }
+
 }