302. Smallest Rectangle Enclosing Black Pixels

src/main/java/algorithms/curated170/hard/smallestrectangleenclosingblackpixels/SmallestRectangleEnclosingBlackPixelsBinarySearch.java

@@ -0,0 +1,38 @@
+package algorithms.curated170.hard.smallestrectangleenclosingblackpixels;
+
+public class SmallestRectangleEnclosingBlackPixelsBinarySearch {
+
+    private char[][] image;
+
+    public int minArea(char[][] image, int x, int y) {
+        this.image = image;
+        int m = image.length, n = image[0].length;
+
+        int bottom = searchBoundary(0, x, 0, n, true, true);
+        int top = searchBoundary(x + 1, m, 0, n, false, true);
+        int left = searchBoundary(0, y, bottom, top, true, false);
+        int right = searchBoundary(y + 1, n, bottom, top, false, false);
+
+        return (right - left) * (top - bottom);
+    }
+
+    private int searchBoundary(int i, int j, int low, int high, boolean findMin, boolean isRow) {
+        while (i != j) {
+            int k = low, mid = (i + j) / 2;
+            while (k < high && isBlack(mid, k, isRow)) {
+                k++;
+            }
+            if ((k < high) == findMin) {
+                j = mid;
+            } else {
+                i = mid + 1;
+            }
+        }
+
+        return i;
+    }
+
+    private boolean isBlack(int mid, int k, boolean isRow) {
+        return ((isRow) ? image[mid][k] : image[k][mid]) == '0';
+    }
+}

src/main/java/algorithms/curated170/hard/smallestrectangleenclosingblackpixels/SmallestRectangleEnclosingBlackPixelsDFS.java

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+package algorithms.curated170.hard.smallestrectangleenclosingblackpixels;
+
+public class SmallestRectangleEnclosingBlackPixelsDFS {
+
+    int left, right, bottom, top;
+    int[][] directions = new int[][] { { 1, 0 }, { -1, 0 }, { 0, 1 }, { 0, -1 } };
+
+    public int minArea(char[][] image, int x, int y) {
+        left = 1000000;
+        right = 0;
+        bottom = 1000000;
+        top = 0;
+        findRectangleBoundaries(image, x, y);
+        return (right - left + 1) * (top - bottom + 1);
+    }
+
+    private void findRectangleBoundaries(char[][] image, int x, int y) {
+        if (isOutOfBoundariesOrBlack(image, x, y)) {
+            return;
+        }
+
+        image[x][y] = '0';
+
+        for (int[] dir : directions) {
+            int nx = x + dir[0];
+            int ny = y + dir[1];
+            findRectangleBoundaries(image, nx, ny);
+        }
+        if (x < left) {
+            left = x;
+        }
+        if (y < bottom) {
+            bottom = y;
+        }
+        if (y > top) {
+            top = y;
+        }
+        if (x > right) {
+            right = x;
+        }
+    }
+
+    private boolean isOutOfBoundariesOrBlack(char[][] image, int x, int y) {
+        return (x < 0 || y < 0 || x >= image.length || y >= image[0].length || image[x][y] == '0');
+    }
+}