二叉树创建#

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// 通过数组创建二叉树，0表示没有结点
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TreeNode* createTreeByArr(int* arr, int len)
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{
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    TreeNode* root= createTreeNode(arr[0]);
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    createTreeByArr_main(arr, len, 1, root ,'l');
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    createTreeByArr_main(arr, len, 2, root ,'r');
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    return root;
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}
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// 递归创建二叉树
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void createTreeByArr_main(int* arr,int len , int i, TreeNode* parent, char RorL)
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{
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    if(i >= len || arr[i]==0)
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    {
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        // 越界了或没有结点
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        return;
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    }
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    TreeNode* node = createTreeNode(arr[i]);
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    if(RorL == 'r')
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    {
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        parent->rchild = node;
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    }
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    else
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    {
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        parent->lchild = node;
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    }
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    createTreeByArr_main(arr, len, 2*(i+1)-1, node, 'l');
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    createTreeByArr_main(arr, len, 2*(i+1), node, 'r');
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}