Go: package main

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

func nextInt(sc *bufio.Scanner) int {
	sc.Scan()
	v, _ := strconv.Atoi(sc.Text())
	return v
}

func min(x, y int) int {
	if x > y {
		return y
	}
	return x
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	n := nextInt(sc)

	P := make([]int, n+1)
	for i := 1; i <= n; i++ {
		l := nextInt(sc)
		P[i-1] = l
		m := nextInt(sc)
		P[i] = m
	}

	matrix := make([][]int, n+1)
	for i := 0; i < n+1; i++ {
		matrix[i] = make([]int, n+1)
	}

	for l := 2; l <= n; l++ {
		for i := 1; i <= n - l + 1; i++ {
			j := i + l - 1
			matrix[i][j] = (1 << 21)
			for k := i; k <= j-1; k++ {
				matrix[i][j] = min(matrix[i][j], matrix[i][k] + matrix[k+1][j] + P[i-1] * P[k] * P[j])
			}
		}
	}
	fmt.Println(matrix[1][n])
}

C++: #include <bits/stdc++.h>
#define all(x) (x).begin(), (x).end()
typedef long long ll;
#define MOD 1000000007
using namespace std;
ll n;
vector<ll> r(100), c(100);
vector<vector<ll> > dp(101, vector<ll>(101, -1));
int dfs(int v, int w) {
    // cout << v << ":" << w << endl;
    if(dp[v][w] != -1) {
        return dp[v][w];
    } else {
        ll tmp = INT_MAX / 3;
        for(int i = v + 1; i < w; i++) {
            tmp = min(tmp, dfs(v, i) + dfs(i, w) + r[v] * r[i] * c[w - 1]);
        }
        dp[v][w] = tmp;
        return tmp;
    }
}
int main() {
    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;
        dp[i][i + 1] = 0;
    }
    dfs(0, n);
    cout << dp[0][n] << endl;
}

C++: #include <iostream>

using namespace std;

const int N = 100;

int min(int a, int b){
    return a > b ? b : a;
}

int main()
{
    int n;
    int rc[N+1];
    int mat[N + 1][N] = {};
    cin >> n;

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

    // 行列の長さl
    for (int l = 2; l < n + 1; l++)
    {
        // i番目の積 積の数は : n - l + 1
        for (int i = 1; i < n - l + 2; i++)
        {
            mat[l][i] = (1 << 21);
            for (int k = 1; k < l; k++)
            {
                mat[l][i] = min(mat[l][i], mat[k][i] + mat[l - k][i + k] + rc[i-1] * rc[i+k-1] * rc[i+l-1]);
            }
        }
    }

    cout << mat[n][1] << endl;
}

C++: #include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll INF = 1e18;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

ll dp[100][100];
vector<pair<int,int>> matrix(100);


ll kukandp(int i, int j){
    if(dp[i][j]!=INF)return dp[i][j];
    if(j-i==0)dp[i][j]=0;
    if(j-i==1)dp[i][j]=matrix[i].first*matrix[i].second*matrix[j].second;

    if(j-i>1){
        for(int k=i; k<j; k++){
            dp[i][j]=min(dp[i][j], kukandp(i,k)+kukandp(k+1,j)+matrix[i].first*matrix[k].second*matrix[j].second);
        }
    }

    return dp[i][j];
}

int main(){
    int N; cin>>N;
    rep(i,N){
        cin>>matrix[i].first>>matrix[i].second;
    }
    rep(i,100)rep(j,100)dp[i][j]=INF;
    cout<<kukandp(0,N-1)<<endl;
    return 0;
}

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;
}