add new solutions

solutions/15/q1536/solution.go

@@ -0,0 +1,44 @@
+// Package q1536 implements a solution for https://leetcode.com/problems/minimum-swaps-to-arrange-a-binary-grid/
+package q1536
+
+func minSwaps(grid [][]int) int {
+	n := len(grid)
+
+	zeros := grid[0] // reuse memory
+	for i := range grid {
+		z := n - 1
+		for z >= 0 && grid[i][z] == 0 {
+			z--
+		}
+		zeros[i] = n - z - 1
+	}
+
+	steps := 0
+	for row := range n - 1 {
+		needZ := n - row - 1
+		if zeros[row] >= needZ {
+			continue
+		}
+
+		// Find a row with at lease needZ zeros at the end
+		found := -1
+		for i := row + 1; i < n; i++ {
+			if zeros[i] >= needZ {
+				found = i
+				break
+			}
+		}
+		if found == -1 {
+			return -1
+		}
+
+		steps += found - row
+		t := zeros[found]
+		copy(zeros[row+1:found+1], zeros[row:found])
+		zeros[row] = t
+	}
+
+	return steps
+}
+
+var _ = minSwaps