Go: package main

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

//util
var sc = bufio.NewScanner(os.Stdin)

func nextStr() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

func printList(list []int) {
	buf := bufio.NewWriter(os.Stdout)
	for _, v := range list {
		buf.Write([]byte(fmt.Sprintf(" %d", v)))
	}
	buf.Write([]byte("\n"))
	buf.Flush()
}

//solve
//単純な場合
func matrixChainMultiplication() {
	//行列が1つだけのとき
	for i := 1; i <= n; i++ {
		m[i][i] = 0
	}
	for l := 2; l <= n; l++ {
		for i := 1; i <= n-l+1; i++ {
			j := i + l - 1
			m[i][j] = 1 << 21
			//kまでで区切る
			for 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])
			}
		}
	}
}

func max(a, b int) int {
	if a > b {
		return a
	} else {
		return b
	}
}

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

const MAX = 100

var n int
var p [MAX + 1]int

//m[i][j]: Mi * Mi+1 * ... * Mjを計算するときに必要なスカラー乗算の最小回数
var m [MAX + 1][MAX + 1]int

func main() {
	sc.Split(bufio.ScanWords)
	n = nextInt()
	for i := 1; i <= n; i++ {

		p[i-1] = nextInt() //行数
		p[i] = nextInt()   //列数
	}

	matrixChainMultiplication()
	fmt.Println(m[1][n])
}

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

static const int N = 100;

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 ; k++){
	if(i == j) m[i][j] = 0;
	else m[i][j] = min(m[i][j], m[i][k] + m[i][k] + m[k + 1][j] + p[i - 1] * p[k] * p[j]);
      }
    }
  }

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

  return 0;
}

C++: #include <iostream>
#include <fstream>
#include <cstdio>
#include <cmath>
#include <vector>
#include <string>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <deque>
#include <bitset>
#include <algorithm>
#include <complex>
#include <array>
#include <iomanip>
using namespace std;

#define REP(i,n) for(int i=0; i<n; ++i)
#define FOR(i,a,b) for(int i=a; i<=b; ++i)
#define FORR(i,a,b) for (int i=a; i>=b; --i)
#define ALL(c) (c).begin(), (c).end()

typedef long long ll;
typedef vector<int> VI;
typedef vector<ll> VL;
typedef vector<long double> VD;
typedef vector<VI> VVI;
typedef vector<VL> VVL;
typedef vector<VD> VVD;
typedef pair<int,int> P;
typedef pair<ll,ll> PL;

template<typename T> void chmin(T &a, T b) { if (a > b) a = b; }
template<typename T> void chmax(T &a, T b) { if (a < b) a = b; }

int in() { int x; scanf("%d", &x); return x; }
ll lin() { ll x; scanf("%lld", &x); return x; }
#define INF 1LL<<60

int main() {
    int N;
    cin >> N;
    vector<P> dim(N);
    REP(i, N) cin >> dim[i].first >> dim[i].second;

    vector< vector<int> > dp(N, vector<int>(N, 1e9));
    vector< vector<P> > mat_size(N, vector<P>(N));
    REP(i, N)
        FOR(j, i, N-1) mat_size[i][j] = make_pair(dim[i].first, dim[j].second);
    REP(i, N) dp[i][i] = 0;
    FOR(l, 1, N - 1) {
        REP(i, N - l) {
            FOR(j, 0, l-1)
                dp[i][i + l] = min(dp[i][i + l],  mat_size[i][i+j].second * mat_size[i][i+j].first * mat_size[i+j+1][i+l].second  + dp[i][i+j] + dp[i+j+1][i+l]);
        }
    }

    // REP(i, N) {
    //     REP(j, N) cerr << dp[i][j] << " ";
    //     cerr << endl;
    // }

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

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

const int MAX = 105;

int main() {
  int n;
  int p[MAX];
  int m[MAX][MAX];
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> p[i-1] >> p[i];
  }

  for (int i = 0; i <= n; i++) {
    m[i][i] = 0;
  }

  for (int i = 2; i <=n; i++) {
    for (int j = 1; j <= n - i + 1; j++) {
      int k = j + i - 1;
      m[j][k] = (1 << 21);
      for (int l = j; l < k; l++) {
        long long tmp = m[j][l] + m[l+1][k] + p[j-1] * p[l] * p[k];
        m[j][k] = m[j][k] > tmp ? tmp : m[j][k];
      }
    }
  }
  cout << m[1][n] << endl;
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define r(i,n) for(auto i=0;i<n;i++)
#define s(c) static_cast<int>((c).size())

int main(){
	int n;
	cin >> n;
	int i, t, A[n+1];
	cin >> A[0] >> A[1];
	for(i = 2; i <= n; i++){
		cin >> t >> A[i];
	}

	//dp[l][r] -> min(A[l]*...*A[r])
	int dp[n][n+1]{}, dplr, l, r;
	for(int i = 1; i <= n; i++){
		for(int j = 0; j < n-i; j++){
			l = j;
			r = j+i;
			dplr = INT_MAX;
			for(int k = l; k < r; k++){
				dplr = min(dplr, dp[l][k] + dp[k+1][r] + A[l]*A[k+1]*A[r+1]);
			}
			dp[l][r] = dplr;
			//printf("[%d, %d]=%d ", l, r, dplr);
		}
		//printf("\n");
	}

	printf("%d\n", dp[0][n]);
}

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<math.h>
using namespace std;
int m[1000][1000];
int p[10000];
#define MAX 10000000
int n;
int x(){
    int q;
    for(int i=0;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]=MAX;
            for(int k=i;k<=j-1;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;
                }
            }
        }
    }return m[1][n];
}
int main(){
   
    cin >> n;
    for(int i=0;i<n;i++){
        cin >> p[i]>>p[i+1];
    }
    cout << x()<<endl;
}

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

int main(){
	int n, x, y;
	cin >> n;
	int a[100][2], c[100][100] = {0};
	for ( int i = 0; i < n; i++ ) 
		cin >> a[i][0] >> a[i][1];
	for (int i = 2; i <= n; i++){
		for (int j = 0; j <= n - i; j++){
			for (int k = 1; k < i; k++){
				y = c[j][k] + c[j+k][i-k] + a[j][0]*a[j+k][0]*a[j+i-1][1];
				x = (x == 0 || x > y) ? y : x;
			}
			c[j][i] = x;
      x = 0;
		}
	}
	cout << c[0][n] << endl;
	return 0;
}