这是一个C ++程序,用于使用动态编程来执行最佳Paranthesization。
Begin Take the length n and dimension of matrix as input. MatrixChain() to find out minimum multiplications: Arguments: a[i][j]=Minimum number of scalar multiplications needed to compute the matrix A[i]A[i+1]...A[j] = A[i..j] where dimension of A[i] is p[i-1] x p[i]. a[i][j] means cost is zero when multiplying one matrix. L is chain length. m = cost / scalar multiplications. Body of the function: for i = 1 to n-1 Initialize a[i][i] = 0 for L = 2 to n-1 for i = 1 to n - L + 1 j = i + L - 1 a[i][j] = INT_MAX for k = i to j - 1 m = a[i][k] + a[k + 1][j] + p[i - 1] * p[k] * p[j]; if (m < a[i][j]) a[i][j] = m b[i][j] = k return a[1][n - 1] End
#include<limits.h> #include<iostream> using namespace std; int MatrixChain(int p[], int n) { int a[n][n]; int b[n][n]; int i, j, k, L, m; for (i = 1; i < n; i++) a[i][i] = 0; for (L = 2; L < n; L++) { for (i = 1; i <= n - L + 1; i++) { j = i + L - 1; a[i][j] = INT_MAX; for (k = i; k <= j - 1; k++) { m = a[i][k] + a[k + 1][j] + p[i - 1] * p[k] * p[j]; if (m < a[i][j]) { a[i][j] = m; b[i][j] = k; } } } } return a[1][n - 1]; } int main() { cout << "输入长度:"; int n; cin >> n; int a[n]; cout << "Enter the dimensions: "; for (int v = 0; v < n; ++v) { cin >> a[v]; } cout << "Minimum number of multiplications is: " << MatrixChain(a,n); return 0; }
输出结果
输入长度:5 Enter the dimensions: 2 3 7 6 4 Minimum number of multiplications is: 174