leetcode -- Search a 2D Matrix -- 重点--BS

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

思路1

思路就是做两次BS. 第一次定位行，第二次定位列

http://blog.csdn.net/linhuanmars/article/details/24216235

python code
http://jelices.blogspot.hk/2014/05/leetcode-python-search-2d-matrix.html

自己重写code

class Solution(object):
    def searchMatrix(self, matrix, target):
        """ :type matrix: List[List[int]] :type target: int :rtype: bool """
        m, n = len(matrix), len(matrix[0])
        low = 0
        high = m - 1

        while low <= high:
            mid = (low + high) / 2
            if matrix[mid][0] == target:
                return True
            elif matrix[mid][0] < target:
                low = mid + 1
            else:
                high = mid - 1
        low -= 1
        x = low
        low, high = 0, len(matrix[x]) - 1

        while low <= high:
            mid = (low + high) / 2
            if matrix[x][mid] == target:
                return True
            elif matrix[x][mid] < target:
                low = mid + 1
            else:
                high = mid - 1
        return False

思路2 直接在matrix上搜索

http://www.cnblogs.com/zuoyuan/p/3770061.html

class Solution:
    # @param matrix, a list of lists of integers
    # @param target, an integer
    # @return a boolean
    def searchMatrix(self, matrix, target):
        i = 0; j = len(matrix[0]) - 1
        while i < len(matrix) and j >= 0:
            if matrix[i][j] == target: return True
            elif matrix[i][j] > target: j -= 1
            else: i += 1
        return False