算法训练第14天|二叉树

翻转二叉树

class Solution {
public:
    TreeNode* invertTree(TreeNode* root) {
        if(root == NULL) return root;
        swap(root->left, root->right);
        invertTree(root->left);
        invertTree(root->right);
    }
};

对称二叉树

class Solution {
public:
    bool compare(TreeNode* left, TreeNode* right)
    {
        if(left == NULL && right != NULL) return false;
        else if(left != NULL && right == NULL) return false;
        else if(left == NULL && right == NULL) return true;
        else if(left->val != right->val) return false;

        bool outside = compare(left->left, right->right);
        bool inside = compare(left->right, right->left);
        bool bSame = outside&&inside;
        return bSame;
    }
    bool isSymmetric(TreeNode* root) {
        if (root == NULL) return false;
        return compare(root->left, root->right);
    }
};

二叉树的最大深度

class Solution {
public:
    int getDepth(TreeNode *root)
    {
        if(root == NULL) return 0;
        int iLeft = getDepth(root->left);
        int iRight = getDepth(root->right);
        int depth = 1 + max(iLeft, iRight);
        return depth;
    }

    int maxDepth(TreeNode* root) {
        if(root == NULL) return 0;
        return getDepth(root);
    }
};

二叉树的最小深度

class Solution {
public:
    int getMinDepth(TreeNode* root)
    {
        if(root == NULL) return 0;
        int iLeft = getMinDepth(root->left);
        int iRight = getMinDepth(root->right);
        if(root->left == NULL && root->right != NULL)
            return 1+iRight;
        if(root->left != NULL && root->right == NULL)
            return 1+iLeft;
        return 1+min(iLeft,iRight);
    }   

    int minDepth(TreeNode* root) {
        if(root == NULL) return 0;
        return getMinDepth(root);
    }
};