Go: package main

/*
連鎖行列積
*/

import (
	"bufio"
	"bytes"
	"fmt"
	"log"
	"math"
	"os"
	"strconv"
	"strings"
)

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

type mem *[][]int

func main() {
	scanner := makeScanner(1024)
	n := eGetInt(scanner)
	p := make([]int, n+1)
	for i := 0; i < n; i++ {
		rowcol := eGetInts(scanner)
		p[i] = rowcol[0]
		p[i+1] = rowcol[1]
	}
	m := make([][]int, n)
	for i := 0; i < n; i++ {
		m[i] = make([]int, n)
	}
	// 初期値の格納
	for i := 0; i < n; i++ {
		for j := i; j < n; j++ {
			if i == j {
				m[i][j] = 0 //  同じ行列へのコストは当然0
			} else {
				m[i][j] = math.MaxInt64
			}
		}
	}

	// num : 行列の数. num == 1の場合は初期値0を格納ずみ
	for num := 2; num <= n; num++ {
		// s : スタート行列番号
		for s := 0; s+num <= n; s++ {
			// t : 終了行列番号
			t := s + num - 1
			// k : 仕切
			for k := s; k < t; k++ {
				m[s][t] = min(m[s][t], m[s][k]+m[k+1][t]+p[s]*p[k+1]*p[t+1])
			}
		}
	}
	fmt.Println(m[0][n-1])
}

////////////////////////////////////////////////////////////////////////////////
// ライブラリ
////////////////////////////////////////////////////////////////////////////////
func makeScanner(maxByte int) *bufio.Scanner {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Buffer(make([]uint8, 0, 8192), maxByte)
	return scanner
}
func makeWordScanner() *bufio.Scanner {
	scanner := makeScanner(8192)
	scanner.Split(bufio.ScanWords)
	return scanner
}
func eGetLine(r *bufio.Scanner) string {
	if r.Scan() {
		return r.Text()
	}
	err := r.Err()
	if err != nil {
		log.Fatal(err)
	}
	// EOF
	return ""
}
func eGetInt(r *bufio.Scanner) int {
	line := eGetLine(r)
	return eAtoi(line)
}
func eGetFields(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Fields(line)
}
func eGetInts(r *bufio.Scanner) []int {
	fields := eGetFields(r)
	ints := make([]int, len(fields))
	for i := 0; i < len(ints); i++ {
		ints[i] = eAtoi(fields[i])
	}
	return ints
}
func eGetChars(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Split(line, "")
}
func eAtoi(s string) int {
	n, err := strconv.Atoi(s)
	if err != nil {
		log.Fatal(err)
	}
	return n
}

type ints []int

func (s ints) String() string {
	var buf bytes.Buffer
	buf.WriteString("[")
	sep := ""
	for _, v := range s {
		buf.WriteString(fmt.Sprintf("%s%d", sep, v))
		sep = ", "
	}
	buf.WriteString("]")
	return buf.String()
}

func reverse(a ints) ints {
	r := make(ints, len(a))
	for i := 0; i < len(a); i++ {
		r[i] = a[len(a)-1-i]
	}
	return r
}
func max(a ints) (int, bool) {
	if len(a) == 0 {
		return 0, false
	}
	m := a[0]
	for _, e := range a {
		if e > m {
			m = e
		}
	}
	return m, true
}

// func min(a []int) int {
// 	m := a[0]
// 	for _, v := range a {
// 		if v < m {
// 			m = v
// 		}
// 	}
// 	return m
// }

func sum(a ints) int {
	if len(a) == 0 {
		return 0
	}
	sum := 0
	for _, e := range a {
		sum += e
	}
	return sum
}
func find(n int, a ints) int {
	for i, v := range a {
		if n == v {
			return i
		}
	}
	return -1
}

C++: #include<iostream>
#include<stdio.h>
#include<algorithm>

using namespace std;

void output( int, int, int, int);

#define MAX 100
#define INFTY (1 << 21)

int SIZE;
int R[MAX + 2];
int C[MAX+1][MAX+1]; // cost table
int B[MAX+1][MAX+1]; // best table

void compute(){
    for ( int i = 1; i <= SIZE; i++ )
    for ( int j = 1; j <= SIZE; j++ ) C[i][j] = INFTY;
    
    for ( int i = 1; i <= SIZE; i++ ) C[i][i] = 0;
    
    for ( int j = 1; j <= SIZE - 1; j++ ){
        for ( int i = 1; i <= SIZE - j; i++ ){
            for ( int k = i + 1; k <= i + j; k++ ){
                // C[i][i+j] = min( C[i][i+j], 
                //                  C[i][k-1] + C[k][i+j] + R[i]*R[k]*R[i+j+1]);
                int cost = C[i][k-1] + C[k][i+j] + R[i]*R[k]*R[i+j+1];
                if ( cost < C[i][i+j] ){
                    C[i][i+j] =  cost;
                    B[i][i+j] = k;
                }
                
            }
        }
    }
}

void order( int i, int j ){
    if ( i == j ) cout << "M" << i;
    else{
        cout << "(";
        order( i, B[i][j]-1 ); order(B[i][j], j);
        cout << ")";
    }
}

void input(){
    cin >> SIZE;
    for ( int i = 1; i <= SIZE + 1; i++ ) cin >> R[i];
}

void output(){
    cout << "minimum cost = " << C[1][SIZE] << endl;
    order(1, SIZE);
    cout << endl;
}

main(){
    input();
    compute();
    output();
}

C++: /**
 * 	matrix chain multiplication
 * 	f(n,m) = multiply Mn*M(n+1)*...*M(m-1)*M(m)
 * 	f(n,n) = 1
 * 	r(n)=c(n-1)
 * 	f(n,n+1) = C(n) * R(n) * C(n+1) = c(n) * c(n-1) * c(n+1)
 * 	f(n,k,m) = f(n,k)*f(k+1,m)*C(n)*r(n)*c(k)
 * 	f(n,m) = min(f(n,k,m)
 */

#include <iostream>
#include <cmath>
#include <climits>

using namespace std;

int r[45] = {0};
int a[100][100] = {0};

int f(int n, int m);
int f(int n, int k, int m);


int f(int n, int k, int m)
{
	return f(n,k) + f(k+1,m) + (r[n] * r[k+1] * r[m+1]);
}

int f(int n, int m)
{
	if (n==m) return 0;
	int & ra = a[n][m];
	if (ra) return ra;
	ra = INT_MAX;
	for (int k=n;k<m;k++)
	{
		int ans = f(n,k,m);
		if (ans < ra) ra = ans;
	}
	return ra;
}

int main()
{
	int rr = 0;
	int cc = 0;
	int n = 0;
	cin >> n;
	for (int i=0;i<n;i++)
	{
		cin >> rr >> cc;
		r[i]=rr;
		r[i+1]=cc;
	}
	for (int i=0;i<n-1;i++)
	{
		a[i][i+1] = r[i] * r[i+1] * r[i+2];
	}
	int ans = f(0,n-1);
	cout << ans << endl;
}

C++: #include<iostream>
#include<climits>
#include<algorithm>
using namespace std;
struct mat{
  int w,h;
};
vector<mat> v;
int memo[101][101];

int solve(int l,int r){
  if(memo[l][r] > 0)return memo[l][r];
  //cout << l << ' ' << r << endl;
  if(l == r)return 0;
  int ret = INT_MAX;
  for(int i = l; i < r; i++){
    int ans = solve(l,i) + solve(i+1,r) + v[l].h * v[i].w * v[r].w;
    ret = min(ret,ans);
  }
  return memo[l][r] = ret;
}
int main(){
  fill(*memo,*(memo+101),-1);
  int n;
  cin >> n;
  for(int i = 0;i < n;i++){
    int r,c;
    cin >> r >> c;
    v.push_back({c,r});
  }
  cout << solve(0,n-1) << endl;
}

C++: #include <bits/stdc++.h>
       
using namespace std;
typedef long long ll;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

struct Size {
  int r, c;
};

int main() {
  int n;
  cin >> n;
  vector<Size> M(n);
  for (int i = 0; i < (int)(n); ++i) cin >> M[i].r >> M[i].c;

  const int INF = 1e9;
  vector<vector<int> > dp(n, vector<int>(n, INF));
  for (int i = 0; i < (int)(n); ++i) dp[i][i] = 0;

  for (int l = 2; l <= n; ++l) {
    for (int i = 0; i < (int)(n); ++i) {
      int j = i + l - 1;
      if (j >= n) continue;
      for (int k = i; k + 1 <= j; ++k) {
        chmin(dp[i][j], dp[i][k] + dp[k + 1][j] + M[i].r * M[k].c * M[j].c);
      }
    }
  }

  cout << dp[0][n - 1] << endl;

  return 0;
}

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

void fnInput(vector<int>& rvnMtrx)
{
  int nMaxSiz;
  cin >> nMaxSiz;
  rvnMtrx.resize(nMaxSiz + 1);

  for (int i = 0; i < nMaxSiz; ++i)
    cin >> rvnMtrx[i] >> rvnMtrx[i + 1];
}

int fnMtrxChainMultpl(vector<vector<int>>& rvvnDetDP, const vector<int>& cnrvnMtrx)
{
  const int nMAXSIZ = cnrvnMtrx.size() - 1;
  for (int i = 1; i <= nMAXSIZ; ++i)  rvvnDetDP[i][i] = 0;

  for (int nDif = 1; nDif <= nMAXSIZ - 1; ++nDif)
    for (int nFrt = 1; nFrt <= nMAXSIZ - nDif; ++nFrt)
    {
      int nBak = nFrt + nDif;
      for (int nx = nFrt; nx <= nBak - 1; ++nx)
        rvvnDetDP[nFrt][nBak] =
          min(rvvnDetDP[nFrt][nBak],
              rvvnDetDP[nFrt][nx] + rvvnDetDP[nx + 1][nBak] 
                                  + cnrvnMtrx[nFrt - 1] * cnrvnMtrx[nx] * cnrvnMtrx[nBak]);
    }
}

int main()
{
  cin.tie(0);
  ios::sync_with_stdio(false);
  vector<vector<int>> vvnDetDP; 
  vector<int> vnMtrx;

  fnInput(vnMtrx);
  vvnDetDP.resize(vnMtrx.size(), vector<int>(vnMtrx.size(), INT_MAX));

  fnMtrxChainMultpl(vvnDetDP, vnMtrx);
  cout << vvnDetDP[1][vnMtrx.size() - 1] << endl;
  return 0;
}