Done

src/04a.js

@@ -0,0 +1,196 @@
+const { inputs } = require("./inputs/04.json");
+
+/**
+ * @param {String} inputStr
+ * @returns {Array} Array of column values for the row
+ */
+function parseRow(inputStr) {
+    const cols = new Array();
+    for (let i = 0; i < inputStr.length; i++) {
+        cols.push(inputStr[i]);
+    }
+    return cols;
+}
+
+/**
+ * @param {Number} rowIdx 
+ * @param {Number} colIdx 
+ * @returns {Boolean} true if the spot is occupied, false if free
+ */
+function checkNW(rowIdx, colIdx) {
+    const row = rows[rowIdx - 1];
+    const value = row[colIdx - 1];
+    if (value === '@') return true;
+    return false;
+}
+
+/**
+ * @param {Number} rowIdx 
+ * @param {Number} colIdx 
+ * @returns {Boolean} true if the spot is occupied, false if free
+ */
+function checkN(rowIdx, colIdx) {
+    const row = rows[rowIdx - 1];
+    const value = row[colIdx];
+    if (value === '@') return true;
+    return false;
+}
+
+/**
+ * @param {Number} rowIdx 
+ * @param {Number} colIdx 
+ * @returns {Boolean} true if the spot is occupied, false if free
+ */
+function checkNE(rowIdx, colIdx) {
+    const row = rows[rowIdx - 1];
+    const value = row[colIdx + 1];
+    if (value === '@') return true;
+    return false;
+}
+
+/**
+ * @param {Number} rowIdx 
+ * @param {Number} colIdx 
+ * @returns {Boolean} true if the spot is occupied, false if free
+ */
+function checkW(rowIdx, colIdx) {
+    const row = rows[rowIdx];
+    const value = row[colIdx - 1];
+    if (value === '@') return true;
+    return false;
+}
+
+/**
+ * @param {Number} rowIdx 
+ * @param {Number} colIdx 
+ * @returns {Boolean} true if the spot is occupied, false if free
+ */
+function checkE(rowIdx, colIdx) {
+    const row = rows[rowIdx];
+    const value = row[colIdx + 1];
+    if (value === '@') return true;
+    return false;
+}
+
+/**
+ * @param {Number} rowIdx 
+ * @param {Number} colIdx 
+ * @returns {Boolean} true if the spot is occupied, false if free
+ */
+function checkSW(rowIdx, colIdx) {
+    const row = rows[rowIdx + 1];
+    const value = row[colIdx - 1];
+    if (value === '@') return true;
+    return false;
+}
+
+/**
+ * @param {Number} rowIdx 
+ * @param {Number} colIdx 
+ * @returns {Boolean} true if the spot is occupied, false if free
+ */
+function checkS(rowIdx, colIdx) {
+    const row = rows[rowIdx + 1];
+    const value = row[colIdx];
+    if (value === '@') return true;
+    return false;
+}
+
+/**
+ * @param {Number} rowIdx 
+ * @param {Number} colIdx 
+ * @returns {Boolean} true if the spot is occupied, false if free
+ */
+function checkSE(rowIdx, colIdx) {
+    const row = rows[rowIdx + 1];
+    const value = row[colIdx + 1];
+    if (value === '@') return true;
+    return false;
+}
+
+function checkAdjacent(rowIdx, colIdx) {
+    let paperCount = 0;
+    const maxRow = rows.length - 1;
+    const maxCol = rows[colIdx].length - 1;
+    if ((rowIdx > 0) && (rowIdx < maxRow)) { // We're not on the top or bottom row so we need to check above and below
+        if ((colIdx > 0) && (colIdx < maxCol)) { // We're not in the leftmost or rightmost spot so we need to check all 8
+            if (checkNW(rowIdx, colIdx)) paperCount++;
+            if (checkN(rowIdx, colIdx)) paperCount++;
+            if (checkNE(rowIdx, colIdx)) paperCount++;
+            if (checkW(rowIdx, colIdx)) paperCount++;
+            if (checkE(rowIdx, colIdx)) paperCount++;
+            if (checkSW(rowIdx, colIdx)) paperCount++;
+            if (checkS(rowIdx, colIdx)) paperCount++;
+            if (checkSE(rowIdx, colIdx)) paperCount++;
+        } else if (colIdx === 0) { // We are in the leftmost column so only check Easterly
+            if (checkN(rowIdx, colIdx)) paperCount++;
+            if (checkNE(rowIdx, colIdx)) paperCount++;
+            if (checkE(rowIdx, colIdx)) paperCount++;
+            if (checkS(rowIdx, colIdx)) paperCount++;
+            if (checkSE(rowIdx, colIdx)) paperCount++;
+        } else if (colIdx === maxCol) { // We are in the rightmost column so only check Westerly
+            if (checkNW(rowIdx, colIdx)) paperCount++;
+            if (checkN(rowIdx, colIdx)) paperCount++;
+            if (checkW(rowIdx, colIdx)) paperCount++;
+            if (checkSW(rowIdx, colIdx)) paperCount++;
+            if (checkS(rowIdx, colIdx)) paperCount++;
+        }
+    } else if (rowIdx === 0) { // We are in the top row so only check Southerly
+        if ((colIdx > 0) && (colIdx < maxCol)) { // We're not in the leftmost or rightmost spot so we need to check all
+            if (checkW(rowIdx, colIdx)) paperCount++;
+            if (checkE(rowIdx, colIdx)) paperCount++;
+            if (checkSW(rowIdx, colIdx)) paperCount++;
+            if (checkS(rowIdx, colIdx)) paperCount++;
+            if (checkSE(rowIdx, colIdx)) paperCount++;
+        } else if (colIdx === 0) { // We are in the leftmost column so only check Easterly
+            if (checkE(rowIdx, colIdx)) paperCount++;
+            if (checkS(rowIdx, colIdx)) paperCount++;
+            if (checkSE(rowIdx, colIdx)) paperCount++;
+        } else if (colIdx === maxCol) { // We are in the rightmost column so only check Westerly
+            if (checkW(rowIdx, colIdx)) paperCount++;
+            if (checkSW(rowIdx, colIdx)) paperCount++;
+            if (checkS(rowIdx, colIdx)) paperCount++;
+        }
+    } else if (rowIdx === maxRow) { // We are in the bottom row so only check Northerly
+        if ((colIdx > 0) && (colIdx < maxCol)) { // We're not in the leftmost or rightmost spot so we need to check all 8
+            if (checkNW(rowIdx, colIdx)) paperCount++;
+            if (checkN(rowIdx, colIdx)) paperCount++;
+            if (checkNE(rowIdx, colIdx)) paperCount++;
+            if (checkW(rowIdx, colIdx)) paperCount++;
+            if (checkE(rowIdx, colIdx)) paperCount++;
+        } else if (colIdx === 0) { // We are in the leftmost column so only check Easterly
+            if (checkN(rowIdx, colIdx)) paperCount++;
+            if (checkNE(rowIdx, colIdx)) paperCount++;
+            if (checkE(rowIdx, colIdx)) paperCount++;
+        } else if (colIdx === maxCol) { // We are in the rightmost column so only check Westerly
+            if (checkNW(rowIdx, colIdx)) paperCount++;
+            if (checkN(rowIdx, colIdx)) paperCount++;
+            if (checkW(rowIdx, colIdx)) paperCount++;
+        }
+    }
+
+    if (paperCount < 4) {
+        return true;
+    } else {
+        return false;
+    }
+}
+
+const rows = new Array();
+inputs.forEach(row => {
+    const cols = parseRow(row);
+    rows.push(cols);
+    return;
+});
+
+let moveableCount = 0;
+for (let rowIdx = 0; rowIdx < rows.length; rowIdx++) {
+    for (let colIdx = 0; colIdx < rows[rowIdx].length; colIdx++) {
+        const row = rows[rowIdx];
+        const value = row[colIdx];
+        if (value === '@') {
+            if (checkAdjacent(rowIdx, colIdx)) moveableCount++;
+        }
+    }
+}
+console.log(moveableCount);