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 <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-1]);
}

C++: #include<bits/stdc++.h>
using namespace std;
main(){
  int a[44],n;
  a[0]=a[1]=1;
  cin>>n;
  for(int i=2;i<=n;i++)a[i]=a[i-1]+a[i-2];
  cout<<a[n]<<endl; 
}

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

struct Mat{
	  int r,c;
};

int main(){

	  int n; cin >> n;
	  vector<Mat> Mats(n);
	  for(int i=0; i<n; i++)
			cin >> Mats[i].r >> Mats[i].c;

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

	  for(int w=1; w<n; w++){
			for(int i=0; i+w<n; i++){
				  int j = i+w;
				  for(int k=i; k<j; k++){
						int num_prod = Mats[i].r * Mats[k+1].r * Mats[i+w].c;
						dp[i][i+w] = min(dp[i][i+w], dp[i][k] + dp[k+1][i+w] + num_prod);
				  }
			}
	  }
/*
	  for(int i=0; i<n; i++){
			for(int j=0; j<n; j++)
				  cout << dp[i][j] << " ";
			cout << endl;
	  }
*/	  
	  cout << dp[0][n-1] << endl;
	  
			
}

C++: #include<iostream>
#include<algorithm>
using namespace std;
void MatrixChain(int *p, int n, int **m, int **s)
{
	for (int i = 1;i <=n;i++)
		m[i][i] = 0;
	for (int r = 2;r <= n;r++)
	{
		for (int i = 1;i <= n - r + 1;i++)
		{
			int j = i + r - 1;
			m[i][j] = m[i + 1][j] + (p[i - 1] * p[i] * p[j]);
			s[i][j] = i;
			for (int k = i + 1;k < j;k++)
			{
				int t = m[i][k] + m[k + 1][j] + (p[i - 1] * p[k] * p[j]);
				if (t < m[i][j])
				{
					m[i][j] = t;
					s[i][j] = k;
				}
			}
		}
	}
}

void print(int i, int j, int **s)
{
	if (i == j)
		cout << "A" << i;
	else
	{
		cout << "(";
		print(i, s[i][j], s);
		print(s[i][j] + 1, j, s);
		cout << ")";
	}
}
int main()
{
	int n;
	cin >> n;
	int *tempP = new int[2 * n]; 
	int *p = new int[n + 1];   
	int **m = new int *[n + 1]; 
	int **s = new int *[n + 1]; 
	for (int i = 1; i <= n; i++)
	{
		m[i] = new int[n + 1];
		s[i] = new int[n + 1];
	}

	for (int i = 0; i < 2 * n; i++)
	{
		cin >> tempP[i];
	}

	for (int i = 0; i <= n; i++)
	{
		p[i] = (i == 0 ? tempP[0] : tempP[i * 2 - 1]);
	}
	MatrixChain(p, n, m, s);
	cout << m[1][n] << endl; 
	return 0;
}

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

int mcm(int p[], int n) {
	int m[n+1][n+1];
	memset(m, 0, sizeof(m));

	for (int s = 0; s < n; s++) {
		for (int i = 1, j = s + 2; j <= n; i++, j++) {
			m[i][j] = 1 << 30;
			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]);
			}
		}
	}
	return m[1][n];
}

int main() {
	int n, d;
	cin >> n;
	int p[n+1];
	for (int i = 0; i < n-1; i++) {
		cin >> p[i] >> d;
	}
	cin >> p[n-1] >> p[n];
	int ans = mcm(p, n);
	cout << ans << endl;
	return 0;
}

C++: #include <cstdio>
#include <climits>

int convert(int p, int size, int n){
    for(int i=1;i<size;i++)p+=n--;
    return p;
}

int multipulication(int *r, int *c, int *count, int p, int size, int n){
    if(size==1)return 0;
    int id = convert(p,size,n);
    if(count[id])return count[id];
    int mlt = INT_MAX;
    int i, tmp;
    for(i=1;i<size;i++){
        tmp = r[p]*r[p+i]*c[p+size-1] + multipulication(r,c,count,p,i,n) + multipulication(r,c,count,p+i,size-i,n);
        if(tmp<mlt)mlt=tmp;
    }
    count[id] = mlt;
    return mlt;
}

int main(){
    int i, n;
    scanf("%d",&n);
    int r[n];
    int c[n];
    int count[n*(n+1)/2];
    for(i=0;i<n*(n+1)/2;i++)count[i]=0;
    for(i=0;i<n;i++)scanf("%d %d",r+i,c+i);
    printf("%d\n",multipulication(r,c,count,0,n,n));
    return 0;
}

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

#define MAX_N 10000
#define INF 10000000LL

long long n, j, x[MAX_N][MAX_N], p[MAX_N + 2];

int matrix() {
	for (int i = 0; i < n; i++) { x[i][i] = 0; }
	for (int h = 2; h <= n; h++) {
		for (int i = 1; i <= n - h + 1; i++) {
			j = i + h - 1;
			x[i][j] = INF;
			for (int k = i; k < j; k++) {
				x[i][j] = min(x[i][j], x[k + 1][j] + p[i - 1] * p[k] * p[j]);
			}
		}
	}
	return x[1][n];
}

int main() {
	cin >> n;
	for (int i = 1; i <= n; i++) {
		cin >> p[i - 1] >> p[i];
	}
	cout << matrix() << 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 <stdlib.h>
#include <stdio.h>

int MCM(int n){
int i,j,k,l,m[101][101],p[101],x;

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]=10000000;
        for(k=i;k<=j;k++){
            x=m[i][k]+m[k+1][j]+p[i-1]*p[k]*p[j];
            if(m[i][j]>x)m[i][j]=x;
            }
        }
    }
return m[i-1][j];
}

int main(){

int i,n,m[101];

scanf("%d",&n);
for(i=0;i<n;i++){
    scanf("%d %d",&m[i],&m[i+1]);
   }
printf("%d\n",MCM(n));
return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
int main(){
	int n,a[101][101];
	int p[101];
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>p[i-1]>>p[i];
	}
	for(int i=1;i<=n;i++)a[i][i]=0;
	for(int l=2;l<=n;l++){
		for(int i=1;i<=n-l+1;i++){
			int j=i+l-1;
			a[i][j]=(1<<21);
			for(int k=i;k<=j-1;k++){
				a[i][j]=min(a[i][j],a[i][k]+a[k+1][j]+p[i-1]*p[k]*p[j]);
			}
		}
	}
	cout<<a[1][n]<<endl;
	return 0;
}