https://wx.233.com/center/extract-question/exercise/ZT2502211851410638120640?type=3&attachType=1

直接搜”sign”

c = Object(l["b"])(),
s = "",
s = "[object FormData]" === Object.prototype.toString.call(n) ? u()("RZRRNN9RXYCP" + c).toUpperCase() : "get" === t ? u()("RZRRNN9RXYCP" + c + decodeURIComponent(a.params)).toUpperCase() : u()("RZRRNN9RXYCP" + c + a.params).toUpperCase(),
e.url = a.url,
e.headers["sid"] = c,
e.headers["sign"] = s,

s -> u()

c -> Object(l["b"])()

        var o = n("d3cd")
          , r = function() {
            var e = new Date
              , t = function(e) {
                return e < 10 ? "0" + e : e
            }
              , n = [e.getFullYear(), e.getMonth(), e.getDate(), e.getHours(), e.getMinutes(), e.getSeconds()].map((function(e) {
                return t(e)
            }
            )).join("")
              , o = parseInt(89999 * Math.random() + 1e4)
              , r = parseInt(89999 * Math.random() + 1e4);
            return "ucpage" + n + o + r
        }

爬取免费题目，此单估价200+。