0074.搜索二维矩阵

https://leetcode.cn/problems/search-a-2d-matrix/

方法一：二分搜索

时间复杂度 $O(\log mn)$，空间复杂度 $O(1)$。

func searchMatrix(matrix [][]int, target int) bool {
	m, n := len(matrix), len(matrix[0])
	for left, right := 0, m*n-1; left <= right; {
		mid := left + (right-left)/2
		row, col := mid/n, mid%n
		if matrix[row][col] == target {
			return true
		} else if matrix[row][col] > target {
			right = mid - 1
		} else {
			left = mid + 1
		}
	}
	return false
}