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和preorder那题相似，只是从后往前遍历的。还是用inorder来的到左边和右边的size，用postorder来的到root public TreeNode build(int[] inorder, int[] postorder, int inStart, int inEnd, int post, HashMap<Integer, Integer> map){ int index = map.get(postorder[post]); int leftSize = index - inStart; int rightSize = inEnd - index; int left = post - rightSize -1; int right = post - 1; TreeNode root = new TreeNode(postorder[post]); if(leftSize > 0) { root.left = build(inorder, postorder, inStart, index-1, left, map); } if(rightSize > 0) { root.right = build(inorder, postorder, index+1, inEnd, right, map); } return root; }

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