代码随想录day16|104.二叉树的最大深度、 111.二叉树的最小深度 、 222.完全二叉树的节点个数

104. 二叉树的最大深度

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */
int maxDepth(struct TreeNode* root) {
    if(!root)
        return 0;
    int left = maxDepth(root->left);
    int right = maxDepth(root->right);

    int maxDepth = left > right ? left : right;
    return maxDepth+1;
}

111. 二叉树的最小深度

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */
int minDepth(struct TreeNode* root) {
    if(!root)
        return 0;
    int left = minDepth(root->left);
    int right = minDepth(root->right);

    if(root->left == NULL && root->right != NULL){
        return 1+right;
    }
    if(root->left != NULL && root->right == NULL){
        return 1+left;
    }
    int result = left < right ? left : right;
    return 1 + result; 
}

222. 完全二叉树的节点个数

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */
int getNode(struct TreeNode* root){
    if(!root)
        return 0;
    int left = getNode(root->left);
    int right = getNode(root->right);
    int result = left + right + 1;
    return result;
}
int countNodes(struct TreeNode* root) {
    return getNode(root);
}

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */

int countNodes(struct TreeNode* root) {
  
  struct TreeNode** stack = (struct TreeNode**)malloc(sizeof(struct TreeNode*) * 100);
    int totalNum = 0;
    int stackTop = 0;
     if(root)
        stack[stackTop++] = root;
    while(stackTop)
    {
        struct TreeNode* cur = stack[--stackTop];
        totalNum++;
        if(cur->left)
            stack[stackTop++] = cur->left;
        if(cur->right)
            stack[stackTop++] = cur->right;

    }
    return totalNum;
}