Add solution #533

Author: JoshCrozier

README.md

@@ -519,6 +519,7 @@
 530|[Minimum Absolute Difference in BST](./solutions/0530-minimum-absolute-difference-in-bst.js)|Easy|
 531|[Lonely Pixel I](./solutions/0531-lonely-pixel-i.js)|Medium|
 532|[K-diff Pairs in an Array](./solutions/0532-k-diff-pairs-in-an-array.js)|Medium|
+533|[Lonely Pixel II](./solutions/0533-lonely-pixel-ii.js)|Medium|
 535|[Encode and Decode TinyURL](./solutions/0535-encode-and-decode-tinyurl.js)|Medium|
 537|[Complex Number Multiplication](./solutions/0537-complex-number-multiplication.js)|Medium|
 538|[Convert BST to Greater Tree](./solutions/0538-convert-bst-to-greater-tree.js)|Medium|

solutions/0533-lonely-pixel-ii.js

@@ -0,0 +1,57 @@
+/**
+ * 533. Lonely Pixel II
+ * https://leetcode.com/problems/lonely-pixel-ii/
+ * Difficulty: Medium
+ *
+ * Given an m x n picture consisting of black 'B' and white 'W' pixels and an integer target,
+ * return the number of black lonely pixels.
+ *
+ * A black lonely pixel is a character 'B' that located at a specific position (r, c) where:
+ * - Row r and column c both contain exactly target black pixels.
+ * - For all rows that have a black pixel at column c, they should be exactly the same as row r.
+ */
+
+/**
+ * @param {character[][]} picture
+ * @param {number} target
+ * @return {number}
+ */
+var findBlackPixel = function(picture, target) {
+  const rows = picture.length;
+  const cols = picture[0].length;
+  const rowCounts = new Array(rows).fill(0);
+  const colCounts = new Array(cols).fill(0);
+  const rowPatterns = new Map();
+
+  for (let row = 0; row < rows; row++) {
+    let blackCount = 0;
+    for (let col = 0; col < cols; col++) {
+      if (picture[row][col] === 'B') {
+        blackCount++;
+        colCounts[col]++;
+      }
+    }
+    rowCounts[row] = blackCount;
+    if (blackCount === target) {
+      const pattern = picture[row].join('');
+      rowPatterns.set(pattern, (rowPatterns.get(pattern) || 0) + 1);
+    }
+  }
+
+  let result = 0;
+  for (let col = 0; col < cols; col++) {
+    if (colCounts[col] === target) {
+      for (let row = 0; row < rows; row++) {
+        if (picture[row][col] === 'B' && rowCounts[row] === target) {
+          const pattern = picture[row].join('');
+          if (rowPatterns.get(pattern) === target) {
+            result += target;
+            break;
+          }
+        }
+      }
+    }
+  }
+
+  return result;
+};