摘要：Problem refer: https://leetcode.com/problems/student-attendance-record-ii/description 阅读全文

摘要：Problem refer: https://leetcode.com/problems/shopping-offers/description/ Official solution refer: https://leetcode.com/problems/shopping-offers/solut 阅读全文

摘要：Problem reference: https://leetcode.com/problems/range-sum-query-2d-immutable 阅读全文

摘要：// Problem Reference: https://leetcode.com/problems/diagonal-traverse /* My sulotion:Sets up x-y coordinates with the matrix.So, it only needs to find 阅读全文