add: 220217-CN [golang]

2202/220217-CN.go

@@ -0,0 +1,39 @@
+package main
+
+import "fmt"
+
+func isValid(n, x, y int) bool {
+	return x >= 0 && y >= 0 && x < n && y < n
+}
+
+func knightProbability(n, k, row, column int) float64 {
+	var dX = [8]int{-2, -1, 1, 2, 2, 1, -1, -2}
+	var dY = [8]int{1, 2, 2, 1, -1, -2, -2, -1}
+	// dp[k -> remaining step][x][y]
+	var dp, dpNext [25][25]float64
+	for i := 0; i < n; i++ {
+		for j := 0; j < n; j++ {
+			dp[i][j] = 1.0
+		}
+	}
+	for i := 0; i < k; i++ {
+		for x := 0; x < n; x++ {
+			for y := 0; y < n; y++ {
+				dpNext[x][y] = 0.0
+				for idx := 0; idx < 8; idx++ {
+					if isValid(n, x+dX[idx], y+dY[idx]) {
+						dpNext[x][y] += dp[x+dX[idx]][y+dY[idx]]
+					}
+				}
+				dpNext[x][y] /= 8.0
+			}
+		}
+		dp = dpNext
+	}
+
+	return dp[row][column]
+}
+
+func main() {
+	fmt.Println(knightProbability(1, 0, 0, 0))
+}