矩阵链乘（ Matrix Chain Multiplication, UVa 442）
#include"pch.h"
#include
#include
#include
#include
using namespace std;
struct Matrix {
int a, b;
Matrix(int a = 0,int b=0):a(a),b(b){}
}m[26];
stack s;
int main() {
int n;
cin >> n;
for (int i = 0; i > name;
int k = name[0] - 'A';
cin >> m[k].a >> m[k].b;
}
string expr;
while (cin >> expr) {
int len = expr.length();
bool error = false;
int ans = 0;
for (int i = 0; i < len; i++) {
if (isalpha(expr[i]))
s.push(m[expr[i] - 'A']);
else if (expr[i] == ')') {
Matrix m2 = s.top();
s.pop();
Matrix m1 = s.top();
s.pop();
if (m1.b != m2.a) {
error = true;
break;
}
ans += m1.a*m1.b*m2.b;
s.push(Matrix(m1.a, m2.b));
}
}
if (error)
printf("error\n");
else
printf("%d\n", ans);
}
return 0;
}
作者：千年暗室 一灯即明
