zoukankan      html  css  js  c++  java
  • POJ3267——The Cow Lexicon(动态规划)

    The Cow Lexicon


    Description
    Few know that the cows have their own dictionary with W (1 ≤ W ≤ 600) words, each containing no more 25 of the characters 'a'..'z'. Their cowmunication system, based on mooing, is not very accurate; sometimes they hear words that do not make any sense. For instance, Bessie once received a message that said "browndcodw". As it turns out, the intended message was "browncow" and the two letter "d"s were noise from other parts of the barnyard.
    The cows want you to help them decipher a received message (also containing only characters in the range 'a'..'z') of length L (2 ≤ L ≤ 300) characters that is a bit garbled. In particular, they know that the message has some extra letters, and they want you to determine the smallest number of letters that must be removed to make the message a sequence of words from the dictionary.
    Input
    Line 1: Two space-separated integers, respectively: W and L
    Line 2: L characters (followed by a newline, of course): the received message
    Lines 3..W+2: The cows' dictionary, one word per line
    Output
    Line 1: a single integer that is the smallest number of characters that need to be removed to make the message a sequence of dictionary words.
    Sample Input
    6 10
    browndcodw
    cow
    milk
    white
    black
    brown
    farmer
    Sample Output
    2

    题目大意:

        题意就是给出一个主串,和一本字典,问最少在主串删除多少字母,可以使其匹配到字典的单词序列.
        PS:是匹配单词序列,而不是一个单词

    解题思路:

        动态规划。网上多数是从后往前推。我从前往后推也AC了。发现更好理解一些。

        具体细节看代码。

    Code:

     1 /*************************************************************************
     2     > File Name: poj3267.cpp
     3     > Author: Enumz
     4     > Mail: 369372123@qq.com
     5     > Created Time: 2014年10月17日 星期五 18时28分18秒
     6  ************************************************************************/
     7 #include<iostream>
     8 #include<cstdio>
     9 #include<cstdlib>
    10 #include<string>
    11 #include<cstring>
    12 #include<list>
    13 #include<queue>
    14 #include<stack>
    15 #include<map>
    16 #include<set>
    17 #include<algorithm>
    18 #define MAXN 1001
    19 using namespace std;
    20 char dic[MAXN][MAXN];
    21 char mes[MAXN];
    22 int dp[MAXN];
    23 int N,M;
    24 int Incl(int i,int j) //判断字典j是否包含在字符串前i位内
    25 {
    26     int Ndic=strlen(dic[j])-1;
    27     if (dic[j][Ndic]!=mes[i]) return -1;
    28     while (1)
    29     {
    30         if (Ndic==-1||i==-1) break;
    31         if (dic[j][Ndic]==mes[i]) i--,Ndic--;
    32         else i--;
    33     }
    34     if (Ndic==-1) return i+1; //返回字典i匹配的第一个字符的位置。
    35     else return -1;
    36 }
    37 int solve()
    38 {
    39     for (int i=0; i<=M-1; i++)
    40     {
    41         if (i!=0)
    42             dp[i]=dp[i-1]+1;
    43         else
    44             dp[i]=1;
    45         for (int j=1; j<=N; j++)
    46         {
    47             int k=Incl(i,j); //判断字典j是否包含在字符串前i位内
    48             if (k!=-1)
    49             {
    50                 //回溯到字符串开头处时,需要特判。注意if语句!WA了好几遍
    51                 if (k-1<0&&dp[i]>i+1-k-strlen(dic[j]))
    52                     dp[i]=(i+1-k-strlen(dic[j]));
    53                 else if (dp[i]>dp[k-1]+i+1-k-strlen(dic[j]))
    54                     dp[i]=dp[k-1]+i+1-k-strlen(dic[j]);
    55             }
    56         }
    57     }
    58     return dp[M-1];
    59 }
    60 int main()
    61 {
    62     while (scanf("%d%d",&N,&M)!=EOF)
    63     {
    64         memset(dp,0,sizeof(dp));
    65         memset(dic,0,sizeof(dic));
    66         memset(mes,0,sizeof(mes));
    67         scanf("%s",mes);
    68         for (int i=1; i<=N; i++)
    69             scanf("%s",dic[i]);
    70         printf("%d
    ",solve());
    71     }
    72     return 0;
    73 }

        

  • 相关阅读:
    一维数组遍历
    实战级Stand-Alone Self-Attention in CV,快加入到你的trick包吧 | NeurIPS 2019
    ThunderNet :像闪电一样,旷视再出超轻量级检测器,高达267fps | ICCV 2019
    Light-Head R-CNN : 旷世提出用于加速two-stage detector的通用结构,速度达102fps
    NASNet : Google Brain经典作,改造搜索空间,性能全面超越人工网络,继续领跑NAS领域 | CVPR 2018
    ICLR 2020 | 抛开卷积,multi-head self-attention能够表达任何卷积操作
    告别炼丹,Google Brain提出强化学习助力Neural Architecture Search | ICLR2017
    AAAI 2020 | 反向R?削弱显著特征为细粒度分类带来提升
    AAAI 2020 | DIoU和CIoU:IoU在目标检测中的正确打开方式
    目标检测 | 经典算法 Cascade R-CNN: Delving into High Quality Object Detection
  • 原文地址:https://www.cnblogs.com/Enumz/p/4095070.html
Copyright © 2011-2022 走看看