Find Longest common Sub-sequence in two strings in O(n) time

public class DebugTest {

public static void main(String[] args) {

char X[] = "AGGTAB".toCharArray();

char Y[] = "GXTXAYB".toCharArray();

System.out.println(findLCS_dp1(X, Y));

X = "XMJYAUZ".toCharArray();

Y = "MZJAWXU".toCharArray();

System.out.println(findLCS_dp1(X, Y));

}

public static int findLCS_dp1(char[] a, char[] b){

int m = b.length;

int n= a.length;

int[] lcs = new int[n+1];

for(int i=1;i<=n;i++){

int prevMatchedValueAtIndexJ = lcs[0];

for(int j=1; j<=m; j++){

int temp = lcs[j] ;

if(a[i-1] == b[j-1])

lcs[j] = 1 + prevMatchedValueAtIndexJ;

else

lcs[j] = Math.max(lcs[j-1], lcs[j]);

prevMatchedValueAtIndexJ = temp;

}

}

return lcs[m];

}

}