右上角标志法

# -*- coding:utf-8 -*-
class Solution:
    # array 二维列表
    def Find(self, target, array):
        # write code here
        if not array: return False
        m = len(array)
        n = len(array[0])
        r, t = n-1, 0
        while 0 <= r and t <= m-1:
            if target == array[t][r]:
                return True
            elif target < array[t][r]:
                r -= 1
            else:
                t += 1
        return False