搜索二维矩阵 II【矩阵】【二分】

Problem: 240. 搜索二维矩阵 II

思路 & 解题方法

暴力、二分、Z

复杂度

时间复杂度:

暴力： $O(mn)$
二分： $O(mlogn)$
Z: $O(m+n)$

空间复杂度:

添加空间复杂度, 示例： $O(n)$

暴力

class Solution:
    def searchMatrix(self, matrix: List[List[int]], target: int) -> bool:
        for x in matrix:
            for num in x:
                if num == target:
                    return True
        return False

二分

class Solution:
    def searchMatrix(self, matrix: List[List[int]], target: int) -> bool:
        for x in matrix:
            left, right = 0, len(matrix[0]) - 1
            while left <= right:
                mid = (left + right) // 2
                if x[mid] > target:
                    right = mid - 1
                elif x[mid] < target:
                    left = mid + 1
                else:
                    return True
        return False

bisect

class Solution:
    def searchMatrix(self, matrix: List[List[int]], target: int) -> bool:
        for x in matrix:
            idx = bisect.bisect_left(x, target)
            if idx < len(x) and x[idx] == target:
                return True
        return False

Z

class Solution:
    def searchMatrix(self, matrix: List[List[int]], target: int) -> bool:
        m, n = len(matrix), len(matrix[0])
        x, y = 0, n - 1
        while x < m and y >= 0:
            if matrix[x][y] == target:
                return True
            if matrix[x][y] > target:
                y -= 1
            elif matrix[x][y] < target:
                x += 1
        return False