算法简记- 二叉树

1、let root = [3,9,20,null,null,15,7]; // 二叉树最小深度 bfs

var minDepth = function(root) {

    if (!root) {
        return 0;
    }
    let deep = 1;
    let queue = [root];
    while (queue.length) {
        let sz = queue.length;
        for (let i = 0; i < sz; i++) {
            let cur = queue.shift();
            if (!cur.left && !cur.right) {
                return deep;
            }
            if (cur.left) {
                queue.push(cur.left);
            }
            if (cur.right) {
                queue.push(cur.right);
            }
        }
        deep++;
    }

};