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 (r Range) length() int {
	return r.end - r.start + 1
}

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[r.start].r, matrices[r.end].c}, v
	}
	if r.length() == 0 {
		panic("must not be empty")
	} else if r.length() == 1 {
		return matrices[r.start], 0
	}

	var minCount int = math.MaxInt32

	for i := 0; i < r.length()-1; i++ {
		formerRange := Range{r.start, r.start + i}
		latterRange := Range{r.start + i + 1, r.end}
		matF, countF := calcMinMatrixChainMultiplication(matrices, formerRange, memo)
		matL, countL := calcMinMatrixChainMultiplication(matrices, latterRange, memo)
		_, countFL := calcMultiplication(matF, matL)
		count := countF + countL + countFL
		if count < minCount {
			minCount = count
		}
	}
	memo[r] = minCount
	return Matrix{matrices[r.start].r, matrices[r.end].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 <stdio.h>
#include <iostream>
using namespace std;

class Matrix{
protected:
	int row;
	int col;
public:
	Matrix(int r, int c){ row = r; col = c; }
	int multiply(Matrix *mat);
	int multiply(Matrix *mat1, Matrix *mat3);
};

int Matrix::multiply(Matrix *mat)
{
	return row * col * mat->col;
}

int Matrix::multiply(Matrix *mat1, Matrix *mat3)
{
	return row * mat1->col * mat3->col;
}

class MatrixChain{
private:
	int len;
	Matrix **chain;
	int mult_num[100][100];
public:
	MatrixChain(int s);
	void addMatrix(Matrix *mat);
	int multiply(int i, int j);
};

MatrixChain::MatrixChain(int s)
{
	len = 0;
	chain = new Matrix*[s];
	for (int i = 0; i < 100; i++) {
		for (int j = 0; j < 100; j++) {
			mult_num[i][j] = 0;
		}
	}
}

void MatrixChain::addMatrix(Matrix *mat)
{
	chain[len] = mat;
	len++;
}

int MatrixChain::multiply(int i, int j)
{
	if (i >= j) return 0;

	if (mult_num[i][j] != 0) return mult_num[i][j];
	
	if (i + 1 == j) {
		mult_num[i][j] = chain[i]->multiply(chain[j]);
		return mult_num[i][j];
	}

	int mult_min;
	for (int k = i; k + 1 <= j; k++) {
		int temp = multiply(i, k) + multiply(k + 1, j);
		temp += chain[i]->multiply(chain[k], chain[j]);		
		if (k == i) mult_min = temp;
		else mult_min = min(temp, mult_min);
	}
	mult_num[i][j] = mult_min;
	return mult_num[i][j];
}

int main(void)
{
	int n;
	cin >> n;
	MatrixChain matc(n);
	for (int i = 0; i < n; i++) {
		int r, c;
		cin >> r >> c;
		matc.addMatrix(new Matrix(r, c));
	}

	cout << matc.multiply(0, n - 1) << endl;

	return 0;
}

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

struct Matrix {
	int r,c;
};

long f(vector<Matrix> &m, int begin, int end, vector<vector<long> > &memo) {
	if (m.size() < 2 || (end - begin) < 2) return 0;
	if (memo[begin][end] != -1) {
		return memo[begin][end];
	}
	if ((end - begin) == 2) {
		return memo[begin][end] = m[begin].r * m[begin].c * m[begin+1].c;
	}
	long common = m[begin].r * m[end-1].c;
	long res	= common * m[begin+1].r + f(m,begin+1,end,memo);
	for (int i=2;i<(end-begin);++i) {
		long t = f(m,begin, begin+i,memo) + f(m,begin+i,end,memo) + common * m[begin+i].r;
		res = min(res, t);
	}
	return memo[begin][end] = res;
}

int main() {
	int n;
	cin >> n;
	vector<Matrix> M(n);
	vector<vector<long> > memo(n);
	for (int i=0;i<n;++i) {
		int r,c;
		cin >> r >> c;
		M[i].r = r; M[i].c = c;
		memo[i].resize(n+1);
		for (int j=0;j<memo[i].size();++j) memo[i][j] = -1;
	}
	cout << f(M, 0, M.size(), memo) << endl;
	return 0;
}

C++: #include<iostream>
#include<map>
#include<vector>
#include<algorithm>
#include<cmath>
#include<climits>
#include<ctime>
#include<cstring>
#include<stack>
#include<queue>
#include<sstream>
#include<string>
#include<set>
#include<array>
#include<cassert>

#define ALL(v) (v).begin(),(v).end()
#define REP(i,p,n) for(int i=p;i<(int)(n);++i)
#define rep(i,n) REP(i,0,n)
#define DUMP(list) cout << "{ "; for(auto nth : list){ cout << nth << " "; } cout << "}" << endl
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i);

using namespace std;

const int MAX=101;
const int INF=1<<29;

int dp[MAX][MAX];
int n;
int c[MAX];
int r[MAX];

int main(){

	fill_n((int *)dp,sizeof(dp)/sizeof(int),INF);
	fill_n((int *)r,sizeof(r)/sizeof(int),0);
	fill_n((int *)c,sizeof(c)/sizeof(int),0);

	cin >> n;

	rep(i,n){
		cin >> r[i] >> c[i];	
	}

	rep(i,n){
		dp[i][i+1] = 0;
	}

	for(int R=2;R<=n;R++){
		for(int L=0;L+R-1<n;L++){
			for(int M=L+1;M<=L+R-1;M++){
				dp[L][L+R] = min(dp[L][L+R],dp[L][M] + dp[M][L+R] + (r[L] * c[M] * c[L+R-1]));
			}
		}
	}

	cout << dp[0][n] << endl;

}

C++: #include <bits/stdc++.h>
using namespace std;
#define Rep(i, n) for (int i = 0; i < (int)(n); i++)
#define BitRep(i, n) for (int i = 0; i < (int)(1 << n); i++)
#define Sum(vec) accumulate(vec.begin(), vec.end(), 0)
#define Sort(vec) sort(vec.begin(), vec.end())
#define Reverse(vec) reverse(vec.begin(), vec.end())
#define Next_permutation(vec) next_permutation(vec.begin(), vec.end())

static const int N = 1000;

int main() {
    int n, p[N + 1], m[N + 1][N + 1];
    cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> p[i - 1] >> p[i];
    }
    for (int i = 1; i <= n; i++) {
        m[i][i] = 0;
    }
    for (int l = 2; l <= n; l++) {
        for (int i = 1; i <= n - l + 1; i++) {
            int j = i + l - 1;
            m[i][j] = (1 << 21);
            for (int k = i; k <= j - 1; k++) {
                m[i][j] = min(m[i][j], m[i][k] + m[k + 1][j] + p[i - 1] * p[k] * p[j]);
            }
        }
    }
    cout << m[1][n] << endl;
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

#define endl '\n'

typedef long long ll;

const ll oo = 0x3f3f3f3f3f3f3f3f;

int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(0);

	int n;
	cin >> n;

	vector<int> v(n + 1);
	for(int i = 0; i < n; ++i)
		cin >> v[i] >> v[n];

	vector<vector<ll>> dp(n + 1, vector<ll>(n + 1, oo));

	for(int l = 0; l < 2; ++l)
		for(int i = 0; i + l <= n; ++i)
			dp[i][i + l] = 0;

	for(int l = 2; l <= n; ++l)
		for(int i = 0; i + l <= n; ++i)
			for(int k = i + 1; k < i + l; ++k)
				dp[i][i + l] = min(dp[i][i + l],
								   dp[i][k] + dp[k][i + l] + (ll) v[k] * v[i] * v[i + l]);

	cout << dp[0][n] << endl;

    return 0;
}