☆打卡算法☆LeetCode 74、搜索二维矩阵 算法解析

示例 1：
输入： matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,60]], target = 3
输出： true

示例 2：
输入： matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,60]], target = 13
输出： false

public class Solution {
        public bool SearchMatrix(int[][] matrix, int target)
        {
            //先列再行二分查找
            int m = matrix.Length;
            //int n = matrix[0].Length;
            int[] firstCol = new int[m];
            for (int i = 0; i < m; i++)
            {
                firstCol[i] = matrix[i][0];
            }
            (int colRes, int left) = binarySerarch(firstCol, target);
            if (colRes >= 0) return true;
            (int res, _) = binarySerarch(matrix[left], target);
            return res > -1;
        }

        private (int res, int left) binarySerarch(int[] arr, int target)
        {
            int left = 0;
            int right = arr.Length - 1;
            while (left <= right)
            {
                int mid = (left + right) / 2;
                if (arr[mid] == target) return (mid, left);
                if (arr[mid] > target) right = mid - 1;
                else left = mid + 1;
            }
            return (-1, left > 0 ? left - 1 : 0);
        }
}