C program to implement Longest Common Sequence

C program to implement Longest Common Sequence

#include<stdio.h>
#include<conio.h>
#include<string.h>

void print_lcs(char b[][20],char x[],int i,int j)
{
	if(i==0 || j==0) return;
	if(b[i][j]=='c')
	{
		print_lcs(b,x,i-1,j-1);
		printf("%c",x[i-1]);
	}
	else if(b[i][j]=='u')
	print_lcs(b,x,i-1,j);
	else
	print_lcs(b,x,i,j-1);
}

void lcs_length(char x[],char y[])
{
	int m,n,i,j,c[20][20];
	char b[20][20];
	m=strlen(x);
	n=strlen(y);
	for(i=0;i<=m;i++)
	{
		c[i][0]=0; c[0][i]=0; }
		for(i=1;i<=m;i++)
		{
			for(j=1;j<=n;j++)
			{
				if(x[i-1]==y[j-1])
				{
					c[i][j]=c[i-1][j-1]+1;
					b[i][j]='c';  //c stands for left up
				}
				else if(c[i-1][j]>=c[i][j-1])
				{
					c[i][j]=c[i-1][j];
					b[i][j]='u';  //u stands for above
				}
				else
				{
					c[i][j]=c[i][j-1];
					b[i][j]='l'; //l stands for left
				}
			}
		}
		print_lcs(b,x,m,n);
		for(i=0;i<m;i++)
		{
			printf("n");
			for(j=0;j<m;j++)
			printf("%d ",c[i][j]);
		}
	}

	
void main()
{
	int i,j;
	char x[20],y[20];
	clrscr();
	printf("1st sequence: ");
	gets(x);
	printf("2nd sequence: ");
	gets(y);
	printf("nLCS are: n");
	lcs_length(x,y);
	printf("n");
	lcs_length(y,x);
	getch();
}