A-M baby

Task/Longest-common-subsequence/JavaScript/longest-common-subsequence-1.js

@@ -0,0 +1,14 @@
+function lcs(a, b) {
+  var aSub = a.substr(0, a.length-1);
+  var bSub = b.substr(0, b.length-1);
+
+  if (a.length == 0 || b.length == 0) {
+    return "";
+  } else if (a.charAt(a.length-1) == b.charAt(b.length-1)) {
+    return lcs(aSub, bSub) + a.charAt(a.length-1);
+  } else {
+    var x = lcs(a, bSub);
+    var y = lcs(aSub, b);
+    return (x.length > y.length) ? x : y;
+  }
+}

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('');
+}

Task/Longest-common-subsequence/JavaScript/longest-common-subsequence-3.js

@@ -0,0 +1,15 @@
+	var t=i;
+	while(i>-1&&j>-1){
+		switch(c[i][j]){
+			default:i--,j--;
+				continue;
+			case (i&&c[i-1][j]):
+				if(t!==i){lcs.unshift(x.substring(i+1,t+1));}
+				t=--i;
+				continue;
+			case (j&&c[i][j-1]): j--;
+				if(t!==i){lcs.unshift(x.substring(i+1,t+1));}
+				t=i;
+		}
+	}
+	if(t!==i){lcs.unshift(x.substring(i+1,t+1));}

Task/Longest-common-subsequence/JavaScript/longest-common-subsequence-4.js

@@ -0,0 +1,27 @@
+function lcs_greedy(x,y){
+	var symbols = {},
+		r=0,p=0,p1,L=0,idx,
+		m=x.length,n=y.length,
+		S = new Buffer(m<n?n:m);
+	p1 = popsym(0);
+	for(i=0;i < m;i++){
+		p = (r===p)?p1:popsym(i);
+		p1 = popsym(i+1);
+		idx=(p > p1)?(i++,p1):p;
+		if(idx===n){p=popsym(i);}
+		else{
+			r=idx;
+			S[L++]=x.charCodeAt(i);
+		}
+	}
+	return S.toString('utf8',0,L);
+	
+	function popsym(index){
+		var s = x[index],
+			pos = symbols[s]+1;
+		pos = y.indexOf(s,pos>r?pos:r);
+		if(pos===-1){pos=n;}
+		symbols[s]=pos;
+		return pos;
+	}
+}