Solution.ts

function deepFilter(obj: Record<string, any>, fn: Function): Record<string, any> | undefined {
    const dfs = (data: any): any => {
        if (Array.isArray(data)) {
            const res = data.map(dfs).filter((item: any) => item !== undefined);
            return res.length > 0 ? res : undefined;
        }
        if (typeof data === 'object' && data !== null) {
            const res: Record<string, any> = {};
            for (const key in data) {
                if (data.hasOwnProperty(key)) {
                    const filteredValue = dfs(data[key]);
                    if (filteredValue !== undefined) {
                        res[key] = filteredValue;
                    }
                }
            }
            return Object.keys(res).length > 0 ? res : undefined;
        }
        return fn(data) ? data : undefined;
    };

    return dfs(obj);
}