Go: package main

import (
	"bufio"
	"fmt"
	"math"
	"os"
	"strconv"
)

type Matrix struct {
	r int // num of row
	c int // num of column
}

type Range struct {
	start int // index, inclusive
	end   int // index, inclusive
}

func calcMultiplication(x, y Matrix) (Matrix, int) {
	if x.c != y.r {
		panic("cannnot calculate")
	}
	return Matrix{x.r, y.c}, x.r * y.c * x.c
}

func calcMinMatrixChainMultiplication(matrices []Matrix, r Range, memo map[Range]int) (Matrix, int) {
	if v, ok := memo[r]; ok {
		return Matrix{matrices[0].r, matrices[len(matrices)-1].c}, v
	}
	if len(matrices) == 0 {
		panic("must not be empty")
	} else if len(matrices) == 1 {
		return matrices[0], 0
	} else if len(matrices) == 2 {
		return calcMultiplication(matrices[0], matrices[1])
	}

	var minCount int = math.MaxInt32

	for i := 0; i < len(matrices)-1; i++ {
		formerMatrices := matrices[:i+1]
		latterMatrices := matrices[i+1:]
		matF, countF := calcMinMatrixChainMultiplication(formerMatrices, Range{0, i}, memo)
		matL, countL := calcMinMatrixChainMultiplication(latterMatrices, Range{i + 1, len(matrices) - 1}, memo)
		_, countFL := calcMultiplication(matF, matL)
		count := countF + countL + countFL
		if count < minCount {
			minCount = count
		}
	}
	return Matrix{matrices[0].r, matrices[len(matrices)-1].c}, minCount
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	n, _ := nextInt(sc)
	matrices := make([]Matrix, n)
	for i := 0; i < n; i++ {
		r, _ := nextInt(sc)
		c, _ := nextInt(sc)
		matrices[i] = Matrix{r, c}
	}
	memo := make(map[Range]int)
	_, resultCount := calcMinMatrixChainMultiplication(matrices, Range{0, len(matrices) - 1}, memo)
	fmt.Println(resultCount)
}

func nextInt(sc *bufio.Scanner) (int, error) {
	sc.Scan()
	return strconv.Atoi(sc.Text())
}

C++: #include <vector>
#include <iostream>
#include <string>
#include <climits>

class M{
  int left, right;
  int cnt;
public:
  M(int l = 0, int r = 0, int c = 0):left(l),right(r),cnt(c){}
  const bool is_init(){return left != 0;}
  int get_l(){return left;}
  int get_r(){return right;}
  int get_c(){return cnt;}
  void show(){std::cout << "[ " << left << "," << cnt << "," << right << " ]";}
  M operator+(M &other){
	  M res(left, other.get_r(), cnt + other.get_c() + left * right * other.get_r());
    return res;
  }
  bool operator>(M &other){
	  return cnt > other.get_c();
  }
};
void show_line(int line){
  std::cout << "start dp line " << line << std::endl;
}
void show_all(std::vector<M> &vec){
  for (auto i = vec.begin(); i != vec.end(); ++i){
    i->show();
    std::cout << "-";
  }
  std::cout << std::endl;
}
M Max(0, 0, INT_MAX);
int dp(std::vector<std::vector<M>> memo){
  if (memo.back().size() != 1){
  	std::vector<M> vec;
  	const int n = memo[0].size() - memo.size();
  	for (auto i = 0; i < n; ++i){
      M min = Max;
  		for (auto j = 0; j < memo.size(); ++j){
  			M temp = memo.at(j).at(i) + memo.at(memo.size() - j - 1).at(i + j + 1);
  			if (min > temp){
  				min = temp;
  			}
  		}
  		vec.push_back(min);
  	}
  	memo.push_back(vec);
  	return dp(memo);
	}else{
    return memo.back().back().get_c();
  }
}
int main(){
  int n;
  std::vector<M> v;
  std::cin >> n;
  for (auto i = 0; i < n; ++i){
	  int a, b;
	  std::cin >> a >> b;
	  v.push_back(M(a, b));
  }
  std::vector<std::vector<M>> memo;
  memo.push_back(v);
  std::cout << dp(memo) << std::endl;
  return 0;

}

C++: #include <iostream>
#include <vector>
#include <climits>

int main() {
	int n;
	std::cin >> n;
	std::vector<int> matSize(n + 1);
	std::cin >> matSize[0] >> matSize[1];
	for (int i = 2; i < n + 1; i++) {
		int dammy;
		std::cin >> dammy >> matSize[i];
	}

	std::vector<std::vector<long>> costMat(n, std::vector<long>(n, 0));
	// 動的計画法により解く
	for (int i = 0; i < n - 1; i++) {
		costMat[i][i + 1] = matSize[i] * matSize[i + 1] * matSize[i + 2];
	}
	for (int i = 2; i < n; i++) {
		for (int j = 0; j < n - i; j++) {
			long min = LONG_MAX;
			for (int k = 0; k < i; k++) {
				long cost = costMat[j][j + k] + costMat[j + k + 1][i + j];
				cost += matSize[j] * matSize[j + k + 1] * matSize[i + j + 1];
				if (cost < min) {
					min = cost;
					costMat[j][i + j] = min;
				}
			}
		}
	}
	std::cout << costMat[0][n - 1] << std::endl;
}

C++: #include<iostream>
#include<algorithm>
#include<vector>
#include<numeric>
#include<string>
using namespace std;

int main(){
	int n; cin >> n;
	vector<int> p(n+1);
	vector<vector<int> > dp(n, vector<int>(n,-1));
	cin >> p[0] >> p[1];
	int a;
	for (int i=0;i<n;i++){
		cin >> a >> p[i+2];
	}
	//前処理
	for (int i=0;i<n;i++) dp[i][i] = 0;
	for (int i=1;i<n;i++) dp[i-1][i] = p[i-1] * p[i] * p[i+1];
	
	//DPの遷移
	for (int i=0;i<n;i++){
		for (int j=0;j<n-i;j++){
			int a = j, b = j + i;
			if (dp[a][b] != -1) continue;
			//実際の処理
			dp[a][b] = 1e9;
			for (int k=a;k<b;k++){
				int now = dp[a][k] + p[a]*p[k+1]*p[b+1] + dp[k+1][b];
				if (dp[a][b] > now)
				dp[a][b] = now;
			}
		}
	}
	
	cout << dp[0][n-1] << endl;
	return 0;

}

C++: #include <algorithm>
#include <iostream>
#include <string>
using namespace std;
static const int MAX = 100;
#define INF (1 << 30);

int store[MAX][MAX] = {{}};

struct matrix {
  int row;
  int col;
};

int nMul(matrix x, matrix y) { return x.row * x.col * y.col; }

matrix mult(matrix x, matrix y) {
  matrix mat;
  mat.row = x.row;
  mat.col = y.col;
  return mat;
}

int main() {
  matrix mat[MAX];
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> mat[i].row;
    cin >> mat[i].col;
  }

  int mcm[MAX][MAX] = {0};

  for (int j = 1; j < n; j++) {
    for (int i = j-1; i >= 0; i--) {
      int minimum = INF;
      for (int k = i; k < j; k++) {
        int joint = nMul(mult(mat[i], mat[k]), mult(mat[k+1], mat[j]));
        int tmp = mcm[i][k] + mcm[k+1][j] + joint;
        minimum = min(minimum, tmp);
      }
      mcm[i][j] = minimum;
    }
  }

  cout << mcm[0][n-1] << endl;
}