LeetCode 598. Range Addition II

You are given an m x n matrix M initialized with all 0's and an array of operations ops, where ops[i] = [ai, bi] means M[x][y] should be incremented by one for all 0 <= x < ai and 0 <= y < bi.

Count and return the number of maximum integers in the matrix after performing all the operations.

Example 1:

Input: m = 3, n = 3, ops = [[2,2],[3,3]]

Output: 4

Explanation: The maximum integer in M is 2, and there are four of it in M. So return 4.

Example 2:

Input: m = 3, n = 3, 

ops = [[2,2],[3,3],[3,3],[3,3],[2,2],[3,3],[3,3],[3,3],[2,2],[3,3],[3,3],[3,3]]

Output: 4

Example 3:

Input: m = 3, n = 3, ops = []

Output: 9

Constraints:

• 1 <= m, n <= 4 * 104

• 0 <= ops.length <= 104

• ops[i].length == 2

• 1 <= ai <= m

• 1 <= bi <= n

• 汗颜啊，写了一大串，直接memory exceed，还是数学快啊。

Runtime: 0 ms, faster than 100.00% of Java online submissions for Range Addition II.

Memory Usage: 42.4 MB, less than 63.10% of Java online submissions for Range Addition II.