236. 二叉树的最近公共祖先c

思想就是层次遍历，然后判断每个节点是否为父节点、

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */
bool judge(struct TreeNode* root,struct TreeNode* q){
    if(!root) return false;
    if(root==q) return true;
    return judge(root->left,q)||judge(root->right,q);
}

struct TreeNode* lowestCommonAncestor(struct TreeNode* root, struct TreeNode* p, struct TreeNode* q) {
    if(root==p||root==q) return root;
    if(judge(p,q)) return p;
    if(judge(q,p)) return q;
    struct TreeNode* queue[5000];
    int front=0,tail=0;
    queue[tail++]=root;
    struct TreeNode* x=root;
    while(front!=tail){
        struct TreeNode* temp=queue[front++];
        if(temp==q||temp==p) break;
        if(judge(temp,p)&&judge(temp,q)) x=temp;
        if(temp->left) queue[tail++]=temp->left;
        if(temp->right) queue[tail++]=temp->right;
    }
    return x;
}

结果：