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