routine

26/02/1009.go

@@ -0,0 +1,12 @@
+package main
+
+import (
+	"math/bits"
+)
+
+func bitwiseComplement(n int) int {
+	if n == 0 {
+		return 1
+	}
+	return n ^ (1<<bits.Len(uint(n)) - 1)
+}

26/03/3070.go

@@ -0,0 +1,35 @@
+package main
+
+import "fmt"
+
+func countSubmatrices(grid [][]int, k int) int {
+	m := len(grid)
+	n := len(grid[0])
+	res := 0
+	perfix := make([][]int, m)
+	for i := range perfix {
+		perfix[i] = make([]int, n)
+	}
+
+	for i := 0; i < m; i++ {
+		for j := 0; j < n; j++ {
+			if i == 0 && j == 0 {
+				perfix[i][j] = grid[0][0]
+			} else if i == 0 {
+				perfix[i][j] = perfix[i][j-1] + grid[i][j]
+			} else if j == 0 {
+				perfix[i][j] = perfix[i-1][j] + grid[i][j]
+			} else {
+				perfix[i][j] = perfix[i-1][j] + perfix[i][j-1] - perfix[i-1][j-1] + grid[i][j]
+			}
+			if perfix[i][j] <= k {
+				res++
+			}
+		}
+	}
+	return res
+}
+
+func main() {
+	fmt.Println(countSubmatrices([][]int{{7, 2, 9}, {1, 5, 0}, {2, 6, 6}}, 18))
+}