hdu 1159 Common Subsequence（最长公共子序列）

Posted 2020-09-07 风中的簌雨

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=1159

Common Subsequence

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 37551    Accepted Submission(s): 17206

Problem Description

A subsequence of a given sequence is the given sequence with some elements (possible none) left out. Given a sequence X = <x1, x2, ..., xm> another sequence Z = <z1, z2, ..., zk> is a subsequence of X if there exists a strictly increasing sequence <i1, i2, ..., ik> of indices of X such that for all j = 1,2,...,k, xij = zj. For example, Z = <a, b, f, c> is a subsequence of X = <a, b, c, f, b, c> with index sequence <1, 2, 4, 6>. Given two sequences X and Y the problem is to find the length of the maximum-length common subsequence of X and Y. 
The program input is from a text file. Each data set in the file contains two strings representing the given sequences. The sequences are separated by any number of white spaces. The input data are correct. For each set of data the program prints on the standard output the length of the maximum-length common subsequence from the beginning of a separate line. 

 

 

Sample Input

abcfbc abfcab

programming contest

abcd mnp

 

 

Sample Output

4

2

0

 

题目大意：求两个串的最长公共子序列长度。

 

解题思路：套用模板。

 

AC代码：

 1 #include <stdio.h>
 2 #include <string.h>
 3 #include <algorithm>
 4 
 5 using namespace std;
 6 
 7 char x[1000], y[1000];
 8 int b[1000][1000], c[1000][1000];
 9 void LCS()
10 {
11     int i,j;
12     int len1 = strlen(x);
13     int len2 = strlen(y);
14     for (i = 0; i <= len1; i ++) b[i][0] = 0;
15     for (j = 0; j <= len2; j ++) b[0][j] = 0;
16     
17     for (i = 1; i <= len1; i ++)
18     {
19         for (j = 1; j <= len2; j ++)
20         {
21             if (x[i-1] == y[j-1])
22                 b[i][j] = b[i-1][j-1] + 1;
23             else
24                 b[i][j] = max(b[i-1][j],b[i][j-1]);
25         }
26     }
27     printf("%d\n",b[len1][len2]);
28 }
29 
30 int main ()
31 {
32     while (scanf("%s%s",x,y)!=EOF)
33     {
34         LCS();
35     }
36     return 0;
37 }