Given an m * n matrix M initialized with all 0’s and several update operations.

Operations are represented by a 2D array, and each operation is represented by an array with two positive integers a and b, which means M[i][j] should be added by one for all 0 <= i < a and 0 <= j < b.

You need to count and return the number of maximum integers in the matrix after performing all the operations.

Example 1: Input: m = 3, n = 3 operations = [[2,2],[3,3]] Output: 4 Explanation: Initially, M = [[0, 0, 0], [0, 0, 0], [0, 0, 0]]

After performing [2,2], M = [[1, 1, 0], [1, 1, 0], [0, 0, 0]]

After performing [3,3], M = [[2, 2, 1], [2, 2, 1], [1, 1, 1]]

So the maximum integer in M is 2, and there are four of it in M. So return 4. Note: The range of m and n is [1,40000]. The range of a is [1,m], and the range of b is [1,n]. The range of operations size won’t exceed 10,000.

思路一：按照最簡單的方式，根據輸入的資料，每次進行矩陣的+1，超時。

思路二：首先找到符合結果的數，即ops操作中有i組就是i，然後找到操作中分別i，j中最小值，返回i*j即可。 類似於求最小交集。