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<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define mod 1000000007
#define MAX 105

ll p[MAX], m[MAX][MAX];

int main(){
    int n; cin >> n;
    for(int i = 0; i <= n; i++){
        int a,b; cin >> a >> b;
        if(i == 0){
            p[i] = a; i++; p[i] = b;
        }else{
            p[i] = b;
        }
    }

    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= n; j++){
            if(i == j) m[i][j] = 0;
            else m[i][j] = INT_MAX;
        }
    }

    for(int len = 2; len <= n; len++){ //計算する行列の個数
        for(int i = 1; i <= n-len+1; i++){ //左端
            int j = i + len -1; //右端
            for(int k = i; k < j; k++){
                m[i][j] = min(m[i][j], m[i][k] + m[k+1][j] + p[i-1]*p[k]*p[j]);
                
            }
        }
    }

    // for(int i = 1; i <= n; i++){
    //     for(int j = 1; j <= n; j++){
    //         cout << m[i][j] << " ";
    //     }
    //     cout << endl;
    // }

    cout << m[1][n] << endl;

    return 0;
}

C++: #include <iostream>
#include <stdio.h>
#define N 101
#define MAX 1 << 21
using namespace std;

int main(int argc, char *argv[])
{
    int n, q;
    scanf("%d", &n);
    int p[N], m[N][N];
    for (int i = 1; i <= n; i++)
    {
        scanf("%d %d", &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; k++)
            {
                q = m[i][k] + m[k + 1][j] + p[i - 1] * p[k] * p[j];
                if (q < m[i][j])
                {
                    m[i][j] = q;
                }
            }
        }
    }

    printf("%d\n", m[1][n]);
    return 0;
}

C++: #include <iostream>
#include <iomanip>
#include <algorithm>
#include <cfloat>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <functional>
#include <sstream>
#include <string>
#include <utility>
#include <map>
#include <memory>
#include <set>
#include <vector>
#include <deque>
#include <list>
#include <stack>
#include <queue>

using namespace std;

class MCMult
{
public:
  vector<vector<int>> mat;
  int solve();
};

int MCMult::solve()
{
  int ms = mat.size();
  vector<vector<int>> dp(ms, vector<int>(ms, 0));

  for ( auto i = 0; i < ms - 1; ++i )
    dp[i][i+1] = mat[i][0] * mat[i][1] * mat[i+1][1];

  for ( auto k = 2; k < ms; ++k )
    {
      for ( auto i = 0; i + k < ms; ++i )
        {
          int ret = dp[i+1][i+k] + mat[i][0] * mat[i][1] * mat[i+k][1];
          ret = min( ret, dp[i][i+k-1] + mat[i+k][0] * mat[i+k][1] * mat[i][0]);
          
          for ( auto j = i + 1; j < i + k - 1; ++j )
            {
              ret = min( ret, dp[i][j] + dp[j+1][i+k] + mat[i][0] * mat[j][1] * mat[i+k][1]);
            }
          dp[i][i+k] = ret;
        }
    }

  cout << dp[0][ms-1] << endl;
  
  return 0;
}

int main()
{
  int n;
  cin >> n;

  MCMult m;

  for ( int i = 0; i < n; ++i )
    {
      int x;
      vector<int> v;
      
      cin >> x;
      v.push_back( x );
      cin >> x;
      v.push_back( x );
      
      m.mat.push_back( v );
    }
  
  m.solve();

  return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i,n) for(int i=0;i<(n);i++)
#define rep2(i,n) for(int i=1;i<=(n);i++)
#define rep3(i,i0,n) for(int i=i0;i<(n);i++)
#define pb push_back
#define mod 1000000007
const ll INF = 1LL << 60;
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; }
ll gcd(ll a, ll b) {return b?gcd(b,a%b):a;}
ll lcm(ll a, ll b) {return a/gcd(a,b)*b;}
#define all(x) x.begin(), x.end()
#define mp make_pair
bool compare(pair<int, int> a, pair<int, int> b) {
    if(a.first != b.first){
        return a.first < b.first;
        
    }else{
        return a.second < b.second;
    }
}


bool In_map(ll y,ll x,ll h,ll w){
    if(y<0 || x<0 || y>=h || x>=w){
        return 0;
    }else{
        return 1;
    }
}
const vector<ll> dx{1,0,-1,0};
const vector<ll> dy{0,1,0,-1};
int main() {
    ll n;
    cin >> n;
    vector<ll> r(n);
    vector<ll> c(n);
    rep(i,n){
        cin >> r[i] >> c[i];
    }

    vector<vector<ll>> dp(n,vector<ll>(n,INF));
    rep(i,n){
        dp[i][i] = 0;
    }
    rep(i,n){
        rep(j,n-i-1){
            rep(k,i+1){
                chmin(dp[j][j+i+1],dp[j][j+k]+dp[j+k+1][j+i+1] + r[j]*c[j+k]*c[j+i+1]);
                //chmin(dp[i][j],dp[i][i+k]+dp[i+k+1][j] + r[i]*c[i+k]*c[j]);
            }
        }

    }

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

}

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

using namespace std;

struct matrix {
  int r;
  int c;
};

// 連鎖行列積問題
int main() {
  vector<matrix> mat;
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) {
    int tmp1,tmp2;
    cin >> tmp1 >> tmp2;
    matrix m = {tmp1, tmp2};
    mat.push_back(m);
  }
  
  int** memo = new int*[n];
  for (int s = 0; s < n; s++) {
    memo[s] = new int[n];
  }

  for (int l = 1; l < n; l++) {
    for (int s = 0; s < n; s++) {
      if (s + l >= n) {
        break;
      }
      
      int minval = (1 << 21);
      int sum = 0;
      for (int i = 0; i < l; i++) {
        sum = memo[s][s+i] + memo[s+i+1][s+l];
        matrix m1 = mat[s];
        matrix m2 = mat[s+i];
        matrix m3 = mat[s+l];

        sum += m1.r * m2.c * m3.c;

        minval = min(minval, sum);
      }
      memo[s][s+l] = minval;
    }
  }

  cout << memo[0][n-1] << endl;
  return 0;
}