add new solutions

solutions/4/q427/solution.go

@@ -0,0 +1,44 @@
+package q427
+
+type Node struct {
+	Val         bool
+	IsLeaf      bool
+	TopLeft     *Node
+	TopRight    *Node
+	BottomLeft  *Node
+	BottomRight *Node
+}
+
+func mkTree(grid [][]int, x, y, w int) *Node {
+	if w == 1 {
+		return &Node{
+			Val:    grid[y][x] == 1,
+			IsLeaf: true,
+		}
+	}
+
+	subtreeW := w / 2
+	node := &Node{
+		TopLeft:     mkTree(grid, x, y, subtreeW),
+		TopRight:    mkTree(grid, x+subtreeW, y, subtreeW),
+		BottomLeft:  mkTree(grid, x, y+subtreeW, subtreeW),
+		BottomRight: mkTree(grid, x+subtreeW, y+subtreeW, subtreeW),
+	}
+	if !node.TopLeft.IsLeaf || !node.TopRight.IsLeaf || !node.BottomLeft.IsLeaf || !node.BottomRight.IsLeaf {
+		return node
+	}
+	if node.TopLeft.Val && node.TopRight.Val && node.BottomLeft.Val && node.BottomRight.Val ||
+		!node.TopLeft.Val && !node.TopRight.Val && !node.BottomLeft.Val && !node.BottomRight.Val {
+		return &Node{
+			Val:    node.TopLeft.Val,
+			IsLeaf: true,
+		}
+	}
+	return node
+}
+
+func construct(grid [][]int) *Node {
+	return mkTree(grid, 0, 0, len(grid))
+}
+
+var _ = construct