Day5

74. Search a 2D Matrix/74. Search a 2D Matrix.csproj

@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+    <RootNamespace>_74._Search_a_2D_Matrix</RootNamespace>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

74. Search a 2D Matrix/Program.cs

@@ -0,0 +1,11 @@
+namespace _74._Search_a_2D_Matrix
+{
+    internal class Program
+    {
+        static void Main(string[] args)
+        {
+            int[][] matrix = new int[][] { new int[] { 1 }};
+            Console.WriteLine(new Solution().SearchMatrix(matrix, 1));
+        }
+    }
+}

74. Search a 2D Matrix/Solution.cs

@@ -0,0 +1,30 @@
+namespace _74._Search_a_2D_Matrix;
+
+public class Solution
+{
+    public bool SearchMatrix(int[][] matrix, int target)
+    {
+        int row = SearchInsert((i) => matrix[i][0], matrix.Length, target);
+        if (row < matrix.Length && matrix[row][0] == target)
+            return true;
+        if (row > 0)
+            row--;
+        int column = SearchInsert((i) => matrix[row][i], matrix[row].Length, target);
+        return column < matrix[row].Length && matrix[row][column] == target;
+    }
+
+    private int SearchInsert(Func<int, int> getByIndex, int len, int target)
+    {
+        int l = -1;
+        int r = len;
+        while (l != r - 1)
+        {
+            int i = (r + l) / 2;
+            if (getByIndex(i) >= target)
+                r = i;
+            else
+                l = i;
+        }
+        return l + 1;
+    }
+}