hdu1159：Common Subsequence dp

題目鏈接：戳這裏

Common Subsequence

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 42990    Accepted Submission(s): 19829

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

 

題意：求兩個字符串的最長公共子串。

題解：裸LCS，連nlogn算法都不用。

代碼：

#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
int read()
{
	char c;int sum=0,f=1;c=getchar();
	while(c<'0' || c>'9'){if(c=='-')f=-1;c=getchar();}
	while(c>='0' && c<='9'){sum=sum*10+c-'0';c=getchar();}
	return sum*f;
}
char s1[1005],s2[1005];
int dp[1005][1005];
int n,m;
int main()
{
	while(scanf("%s%s",s1,s2)!=EOF)
	{
		n=strlen(s1);m=strlen(s2);
		memset(dp,0,sizeof(dp));
		for(int i=1;i<n;i++)
		for(int j=1;j<m;j++)
		{
			if(s1[i-1]==s2[j-1])
			dp[i][j]=dp[i-1][j-1]+1;
			else
			dp[i][j]=max(dp[i-1][j],dp[i][j-1]);
		}
		cout<<dp[n][m]<<endl;
	}
	return 0;
}