303题目采用线段树解答

src/main/java/com/ximo/datastructuresinaction/leetcode/solution303/NumArray2.java

@@ -0,0 +1,28 @@
+package com.ximo.datastructuresinaction.leetcode.solution303;
+
+import com.ximo.datastructuresinaction.segmenttree.SegmentTree;
+
+/**
+ * @author xikl
+ * @date 2019/1/8
+ */
+public class NumArray2 {
+
+
+    private SegmentTree<Integer> segmentTree;
+
+    public NumArray2(int[] nums) {
+        Integer[] newNums = new Integer[nums.length];
+        for (int i = 0; i < nums.length; i++) {
+            newNums[i] = nums[i];
+        }
+
+        segmentTree = new SegmentTree<>(newNums, (next, prev) -> next + prev);
+    }
+
+    public int sumRange(int i, int j) {
+        return segmentTree.queryRangeClose(i, j);
+    }
+
+
+}