leetcode 第 402 题,移除 K 位数字 的疑问 - V2EX
yujianwjj

leetcode 第 402 题,移除 K 位数字 的疑问

  •  
  •   yujianwjj May 30, 2023 3440 views
    This topic created in 1087 days ago, the information mentioned may be changed or developed.

    这道题目的解法是 每次删除一个字符,使剩下的字符最小。然后执行 k 次。

    这道题目为什么贪心算法是最优解?怎么证明。

    4 replies    2023-05-31 03:19:15 +08:00
    JasonLaw
        1
    JasonLaw  
       May 30, 2023
    题目链接: https://leetcode.com/problems/remove-k-digits/

    Greedy? 不应该是 Monotonic Stack 吗?

    你应该把你的 solution 发出来,这样子才能有正确性的证明,建议你 append 一下。
    JasonLaw
        2
    JasonLaw  
       May 30, 2023
    NeetCode 的讲解。

    cpstar
        3
    cpstar  
       May 30, 2023
    看视频理解了题目,但是不赞同在数字大小上做文章,相反,直接干枚举。
    我感觉,应该是,在 num ( m 长)中取 m-k 个数字,然后求最小?
    有啥问题?
    kayleh
        4
    kayleh  
       May 31, 2023 via Android
    1. 只能移除数字,数字的原本顺序无法改变,所以 1432219 移除 3 位的有效答案只能是 1219 ,而不是 1123 。所以只能顺序遍历构造答案。
    2. 组成最小数字的数位应该是递增的(单调栈)
    3. 优先从左到右构造数字(尽量让高位的数较小)对答案贡献越大(贪心)
    About     Help     Advertise     Blog     API     FAQ     Solana     1161 Online   Highest 6679       Select Language
    创意工作者们的社区
    World is powered by solitude
    VERSION: 3.9.8.5 332ms UTC 17:56 PVG 01:56 LAX 10:56 JFK 13:56
    Do have faith in what you're doing.
    ubao msn snddm index pchome yahoo rakuten mypaper meadowduck bidyahoo youbao zxmzxm asda bnvcg cvbfg dfscv mmhjk xxddc yybgb zznbn ccubao uaitu acv GXCV ET GDG YH FG BCVB FJFH CBRE CBC GDG ET54 WRWR RWER WREW WRWER RWER SDG EW SF DSFSF fbbs ubao fhd dfg ewr dg df ewwr ewwr et ruyut utut dfg fgd gdfgt etg dfgt dfgd ert4 gd fgg wr 235 wer3 we vsdf sdf gdf ert xcv sdf rwer hfd dfg cvb rwf afb dfh jgh bmn lgh rty gfds cxv xcv xcs vdas fdf fgd cv sdf tert sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf sdf shasha9178 shasha9178 shasha9178 shasha9178 shasha9178 liflif2 liflif2 liflif2 liflif2 liflif2 liblib3 liblib3 liblib3 liblib3 liblib3 zhazha444 zhazha444 zhazha444 zhazha444 zhazha444 dende5 dende denden denden2 denden21 fenfen9 fenf619 fen619 fenfe9 fe619 sdf sdf sdf sdf sdf zhazh90 zhazh0 zhaa50 zha90 zh590 zho zhoz zhozh zhozho zhozho2 lislis lls95 lili95 lils5 liss9 sdf0ty987 sdft876 sdft9876 sdf09876 sd0t9876 sdf0ty98 sdf0976 sdf0ty986 sdf0ty96 sdf0t76 sdf0876 df0ty98 sf0t876 sd0ty76 sdy76 sdf76 sdf0t76 sdf0ty9 sdf0ty98 sdf0ty987 sdf0ty98 sdf6676 sdf876 sd876 sd876 sdf6 sdf6 sdf9876 sdf0t sdf06 sdf0ty9776 sdf0ty9776 sdf0ty76 sdf8876 sdf0t sd6 sdf06 s688876 sd688 sdf86