php多维数组去掉重复值示例分享

代码如下:
<?php
$json='{

    "rec_items": [
        {
            "classes": "玄幻",
            "gid": 6326585,
            "author": "我吃西红柿",
            "nid": 10079306,
            "last_sort": 841,
            "last_chapter_name": "第二十五卷 第六章 一扫而空",
            "sub_count": 5364424,
            "novel_name": "莽荒纪",
            "last_update_time": 1393679718826
        },
        {
            "classes": "玄幻",
            "gid": 6109786,
            "author": "唐家三少",
            "nid": 10079046,
            "last_sort": 1153,
            "last_chapter_name": "第三百八十一章 开始行动（中）",
            "sub_count": 3933876,
            "novel_name": "绝世唐门",
            "last_update_time": 1393681654511
        },
        {
            "classes": "玄幻",
            "gid": 10645516,
            "author": "辰东",
            "nid": 12649548,
            "last_sort": 478,
            "last_chapter_name": "第四百三十二章 扛媳妇回村",
            "sub_count": 1422482,
            "novel_name": "完美世界",
            "last_update_time": 1393681655610
        },
        {
            "classes": "玄幻",