10405 - Longest Common Subsequence

Problem C: Longest Common Subsequence

Sequence 1:

Sequence 2:


Given two sequences of characters, print thelength of the longest common subsequence of both sequences. Forexample, the longest common subsequence of the following twosequences:

abcdgh
aedfhr

is adh of length 3.

Input consists of pairs of lines. The first line of a pair containsthe first string and the second line contains the second string. Eachstring is on a separate line and consists of at most 1,000 characters

For each subsequent pair of input lines, output a line containing oneinteger number which satisfies the criteria stated above.

Sample input

a1b2c3d4e
zz1yy2xx3ww4vv
abcdgh
aedfhr
abcdefghijklmnopqrstuvwxyz
a0b0c0d0e0f0g0h0i0j0k0l0m0n0o0p0q0r0s0t0u0v0w0x0y0z0
abcdefghijklmnzyxwvutsrqpo
opqrstuvwxyzabcdefghijklmn

Output for the sample input

4
3
26
14

#include<stdio.h>
#include<string.h>
#define max(x,y) ((x)>(y)?(x):(y))
char a[1005],b[1005];
int f[1005][1005],i,j;
int main()
{
	while(gets(a)&&gets(b))
	{
		memset(f,0,sizeof(f));
		for(i=1;i<=strlen(a);i++)
			for(j=1;j<=strlen(b);j++)
				if(a[i-1]==b[j-1])
					f[i][j]=f[i-1][j-1]+1;
				else
					f[i][j]=max(f[i-1][j],f[i][j-1]);
		printf("%d\n",f[strlen(a)][strlen(b)]);
	}
	return 0;
}