add new solutions

solutions/2/q221/solution.go

@@ -0,0 +1,26 @@
+package q221
+
+func maximalSquare(matrix [][]byte) int {
+	w, h := len(matrix[0]), len(matrix)
+
+	maxSq := make([]int16, w+h)
+	maxV := make([]int16, w)
+	ret := 0
+	for y := range h {
+		var maxH int16
+		for x := range w {
+			if matrix[y][x] == '0' {
+				maxH, maxV[x], maxSq[x-y+h] = 0, 0, 0
+				continue
+			}
+
+			maxH++
+			maxV[x]++
+			maxSq[x-y+h] = min(maxH, maxV[x], maxSq[x-y+h]+1)
+			ret = max(ret, int(maxSq[x-y+h]))
+		}
+	}
+	return ret * ret
+}
+
+var _ = maximalSquare