2018多校第一場A——Monotonic Matrix

連接：https://www.nowcoder.com/acm/contest/139/A 來源：牛客網  c++ 題目描述 Count the number of n x m matrices A satisfying the following condition modulo (109+7). * Ai, j ∈ {0, 1, 2} for all 1 ≤ i ≤ n, 1 ≤ j ≤ m.

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