A-M baby

Task/Longest-common-subsequence/JavaScript/longest-common-subsequence-2.js

@@ -0,0 +1,35 @@
+function lcs(x,y){
+	var s,i,j,m,n,
+		lcs=[],row=[],c=[],
+		left,diag,latch;
+	//make sure shorter string is the column string
+	if(m<n){s=x;x=y;y=s;}
+	m = x.length;
+	n = y.length;
+	//build the c-table
+	for(j=0;j<n;row[j++]=0);
+	for(i=0;i<m;i++){
+		c[i] = row = row.slice();
+		for(diag=0,j=0;j<n;j++,diag=latch){
+			latch=row[j];
+			if(x[i] == y[j]){row[j] = diag+1;}
+			else{
+				left = row[j-1]||0;
+				if(left>row[j]){row[j] = left;}
+			}
+		}
+	}
+	i--,j--;
+	//row[j] now contains the length of the lcs
+	//recover the lcs from the table
+	while(i>-1&&j>-1){
+		switch(c[i][j]){
+			default: j--;
+				lcs.unshift(x[i]);
+			case (i&&c[i-1][j]): i--;
+				continue;
+			case (j&&c[i][j-1]): j--;
+		}
+	}
+	return lcs.join('');
+}