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;
int p[105];
int m[110][110];
int n;

int main() {
	cin >> n;
	for (int i = 1; i <= n; i++) {
		cin >> p[i - 1];
		cin >> p[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] = (i << 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] << "\n";
	return 0;
}

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

int	main()
{
	int	cnt[100][100];
	int	n;
	cin >> n;
	for (int i = 0; i < n; ++i) {
		for (int j = 0; j < n; ++j)
			cnt[i][j] = -1;
		cnt[i][i] = 0;
	}
	vector<int>	r_vec(n), c_vec(n);
	for (int i = 0; i < n; ++i)
		cin >> r_vec.at(i) >> c_vec.at(i);
	for (int i = 1; i < n; ++i) {
		int	k;
		for (int j = 0; (k = i + j) < n; ++j) {
			for (int l = j; l < k; ++l) {
				int	tmp_cnt = cnt[j][l] + cnt[l + 1][k];
				tmp_cnt += r_vec.at(j) * c_vec.at(l) * c_vec.at(k);
				if (cnt[j][k] == -1 || cnt[j][k] > tmp_cnt)
					cnt[j][k] = tmp_cnt;
			}
		}
	}
	cout << cnt[0][n - 1] << endl;
}

C++: #include<cstdio>
#include<algorithm>
using namespace std;
static const int N=100;
int main(){
  int n,p[N+1],m[N+1][N+1];
  scanf("%d",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-1+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]);
      }
    }
  }
  printf("%d\n",m[1][n]);
  return 0;
}

C++: #include "bits/stdc++.h"

using namespace std;

using ll = long long;
using ld = long double;
using P = pair<string, int>;
constexpr ld EPS = 1e-12;
constexpr int INF = numeric_limits<int>::max() / 2;
constexpr int MOD = 1e9 + 7;

template <typename T>
void printv(const vector<T> &v)
{
    int sz = v.size();
    for (int i = 0; i < sz; i++)
    {
        cout << v[i] << " \n"[i == sz - 1];
    }
}

int n;
vector<ll> r(100), c(100);
ll dp[100][100];

// dp[l][r]
ll calc(int lx, int rx)
{
    if (dp[lx][rx] != 1e15)
    {
        return dp[lx][rx];
    }
    for (int i = lx; i < rx; i++)
    {
        dp[lx][rx] = min(dp[lx][rx], calc(lx, i) + calc(i + 1, rx) + r[lx] * c[i] * c[rx]);
    }
    return dp[lx][rx];
}

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

    cin >> n;
    for (int i = 0; i < n; i++)
        cin >> r[i] >> c[i];
    for (int i = 0; i < n; i++)
    {
        dp[i][i] = 0;
        for (int j = i + 1; j < n; j++)
        {
            dp[i][j] = 1e15;
        }
    }
    cout << calc(0, n - 1) << endl;
}

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

int main()
{
	int n;
	int v[101];
	long m[100][100];
	const long nil = 999999999;

	cin >> n;

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

	for (int i = 0; i < 100; i++)
		for (int j = 0; j < 100; j++)
			if (i == j)
				m[i][j] = 0;
			else
				m[i][j] = nil;
	
	for(int i = n - 2; i > -1; i--)
		for(int j = i + 1; j < n; j++)
			for (int k = i; k < n; k++)
				m[i][j] = min(m[i][j], m[i][k] + m[k + 1][j] + v[i] * v[k + 1] * v[j + 1]);

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

	return 0;
}

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

struct mat {
	ll l, c, r;
};

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

	mat a[110][110];
	int N; cin >> N;
	ll l, r;
	for (int i = 0; i < N; i++) {
		cin >> l >> r;
		a[i][i].l = l;
		a[i][i].r = r;
		a[i][i].c = 0;
	}
	for (int l = 1; l < N;l++) {
		for (int i = 0; i+l < N; i++) {
			ll m = 1000010;
			a[i][i + l].l = a[i][i].l;
			a[i][i + l].r = a[i + l][i + l].r;
			for (int j = i; j < i + l; j++) {
				m = min(a[i][j].l * a[i][j].r * a[j + 1][i + l].r + a[i][j].c + a[j + 1][i + l].c, m);
			}
			a[i][i + l].c = m;
		}
	}
	cout << a[0][N-1].c << endl;
}

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

static const int N = 1000;

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

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 <bits/stdc++.h>

#define rep(i, n) for(int i = 0; i < n; i++)
using namespace std;

typedef long long ll;

const int INF = 1 << 30;
const ll LLINF = 1LL << 62;

int mod = 1000000007;

int main(void){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    //A*Bの行列とB*Cの行列、計A*B*C回の乗算をしてA*Cの行列になる
    int N; cin >> N;
    int R[N], C[N]; rep(i, N) cin >> R[i] >> C[i];
    int dp[N+1][N+1];
    rep(i, N+1) rep(j, N+1) dp[i][j] = INF;
    rep(i, N+1) dp[i][i+1] = 0;
    for(int haba = 2; haba <= N; haba++){
        for(int left = 0; left < N; left++){
            int right = left + haba;
            if(right > N) break;
            for(int boarder = left+1; boarder <= right-1; boarder++){
                dp[left][right] = min(dp[left][right], dp[left][boarder] + dp[boarder][right] + R[left]*C[boarder-1]*C[right-1]);
            }
        }
    }

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