re-added solution

DynamicProgramming/extras.js

@@ -1,6 +1,14 @@
 // Recursive solution - not nearly as good as DP.
 
+var cache = [];
+for (var i = 0; i < size; i++) {
+  cache.push([]);
+}
+
 var recurse = function(row, col) {
+  if (cache[row][col] !== undefined) {
+    return cache[row][col];
+  }
   if (row === size - 1) {
     return {
       cost: input[row][col],
@@ -30,10 +38,12 @@ var recurse = function(row, col) {
     choice = center;
   }
 
-  return {
+  var retVal = {
     cost: choice.cost + input[row][col],
     path: [col].concat(choice.path)
   };
+  cache[row][col] = retval;
+  return retval;
 };
 
 var bestPath = null;

DynamicProgramming/solution.js

@@ -26,6 +26,19 @@ var size = 12;
 
 var findMinimumPath = function(input) {
 
+  // Dynamic programming woo!
+  for (var row = size - 2; row >= 0; row--) {
+    for (var col = 0; col < size; col++) {
+
+      var left = input[row+1][col-1] || Infinity;
+      var center = input[row+1][col];
+      var right = input[row+1][col+1] || Infinity;
+
+      // Update the square above these choices.
+      input[row][col] += Math.min.apply(null, [left, center, right]);
+    }
+  }
+
   // This is the "greedy" solution - it's not very good, because
   // it never "looks ahead" to the rows yet to come.
   // But it might be of some help to you as you write your own!