Go: package main

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

const (
	initialBufSize = 100000
	maxBufSize     = 1000000
)

var sc *bufio.Scanner

func initScanner(r io.Reader) *bufio.Scanner {
	buf := make([]byte, initialBufSize)

	sc := bufio.NewScanner(r)
	sc.Buffer(buf, maxBufSize)
	sc.Split(bufio.ScanWords) // bufio.ScanLines
	return sc
}

func main() {
	sc = initScanner(os.Stdin)
	fmt.Println(resolve(parseProblem()))
}

type matrixSize struct{ row, col int }

func calcNum(i, j matrixSize) int {
	return i.row * j.col * i.col
}

func parseProblem() (int, []matrixSize) {
	n := scanInt(sc)
	sizes := make([]matrixSize, n)
	for i := 0; i < n; i++ {
		sizes[i] = matrixSize{row: scanInt(sc), col: scanInt(sc)}
	}
	return n, sizes
}

var dp [][]int

func initDP(n int) {
	dp = make([][]int, n+1)
	for i := 0; i < len(dp); i++ {
		dp[i] = make([]int, n+1)
		for j := 0; j < len(dp[i]); j++ {
			dp[i][j] = math.MaxInt64
		}
	}
}

func resolve(n int, sizes []matrixSize) int {
	// TODO 復習
	initDP(n)
	_rec(sizes, 0, n)
	return dp[0][n]
}

func _rec(sizes []matrixSize, l, r int) int {
	if dp[l][r] != math.MaxInt64 {
		return dp[l][r]
	}
	if r-l <= 1 {
		dp[l][r] = 0
		return 0
	}
	num := math.MaxInt64
	for i := l + 1; i < r; i++ {
		v := _rec(sizes, l, i) + _rec(sizes, i, r) + calcNum(matrixSize{sizes[l].row, sizes[i].row}, matrixSize{sizes[i].row, sizes[r-1].col})
		if v < num {
			num = v
		}
	}
	dp[l][r] = num
	return dp[l][r]
}

// snip-scan-funcs
func scanInt(sc *bufio.Scanner) int {
	sc.Scan()
	i, _ := strconv.Atoi(sc.Text())
	return int(i)
}
func scanString(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

C++: #include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
#include<string>
#include<vector>
#include<stack>
#include<bitset>
#include<cstdlib>
#include<cmath>
#include<set>
#include<list>
#include<deque>
#include<map>
#include<queue>
#define LL long long
using namespace std;
int main()
{
    int a[200],n,m[200][200],i;
    cin>>n;
    for (i=1; i<=n; i++)
    {
        cin>>a[i-1]>>a[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]+a[i-1]*a[k]*a[j]);
            }
        }
    }
    cout<<m[1][n]<<endl;
    return 0;
}

C++: #define _USE_MATH_DEFINES

#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <map>
#include <list>

long long int INF = 1e18;
using namespace std;

typedef pair<long long int, long long int> P;

int main(){
	
	int n;
	cin >> n;
	
	int A[200], B[200];
	
	for(int i = 0; i < n; i++){
		cin >> A[i] >> B[i];
	}
	
	long long int DP[101][101] = {};
	for(int i = 1; i < n; i++){
		for(int j = 0; j + i < n; j++){
			DP[j][j + i] = INF;
			for(int k = 0; k < i; k++){
				DP[j][j + i] = min(DP[j][j + i], DP[j][j + k] + DP[j + k + 1][j + i] + A[j] * B[j + k] * B[j + i]);
				//cout << DP[j][j + k] + DP[j + k + 1][j + i] + A[j + k] * B[j + k] * B[j + k + 1] << " ";
			}
			//cout << DP[j][j + i] << " ";
		}
		//cout << endl;
	}
	
	cout << DP[0][n - 1] << endl;
	
	return 0;
}

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;
}