题目分析

题目的意思非常简单，就是给定一个矩阵乘法的表达式然后计算就可以了。随便写写

AC代码

#include <iostream>
#include <deque>
#include <vector>
#include <string>
#include <unordered_map>using namespace std;int ans;class Matrix {int row, colum;
public:Matrix(int _row, int _colum) : row(_row), colum(_colum) {}friend Matrix operator * (const Matrix &lhs, const Matrix &rhs);
};Matrix operator * (const Matrix &lhs, const Matrix &rhs) {if (lhs.colum != rhs.row) {ans = -1;return Matrix(0, 0);}ans += lhs.row * lhs.colum * rhs.colum;return Matrix(lhs.row, rhs.colum);
}int n;
unordered_map<char, Matrix> matrixs;
deque<Matrix> s;int main() {ios::sync_with_stdio(false);cin >> n;int row, colum;string var;for (int i = 0; i < n; ++i) {cin >> var >> row >> colum;matrixs.insert({var[0], Matrix(row, colum)});}while (cin >> var) {ans = 0;s.clear();bool error = false;for (auto c : var) {if (c == '(') {} else if (c == ')') {Matrix a = s.back();s.pop_back();Matrix b = s.back();s.pop_back();//需要注意是b * as.push_back(b * a);if (ans == -1) {error = true;break;}} else {s.push_back(matrixs.at(c));}}if (error) {cout << "error\n";} else {cout << ans << "\n";}}return 0;
}