PKUOJ1458 Common Subsequence

 

Common Subsequence

Time Limit: 1000MS Memory Limit: 10000KTotal Submissions: 20787 Accepted: 7902

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, x_ij = 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.

Input

The program input is from the std input. Each data set in the input contains two strings representing the given sequences. The sequences are separated by any number of white spaces. The input data are correct.

Output

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

【思路】经典的DP问题，求最长公共子串的长度

#include<string>#include<iostream>using namespace std;#define max(x,y) ((x)>(y)?(x):(y))int rst[300][300];int main(){ //ifstream cin("test.txt"); string str1,str2; int i,j,len1,len2; while(cin>>str1>>str2) {    memset(rst,0,sizeof(rst));  len1 = str1.length();  len2 = str2.length();    for(i=0;i<len1;i++)   for(j=0;j<len2;j++)    if(str1[i] == str2[j])     rst[i+1][j+1] = rst[i][j] + 1;    else     rst[i+1][j+1] = max(rst[i+1][j],rst[i][j+1]);  cout<<rst[len1][len2]<<endl;   } return 0;}