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 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[0].r, matrices[len(matrices)-1].c}, v
	}
	if len(matrices) == 0 {
		panic("must not be empty")
	} else if len(matrices) == 1 {
		return matrices[0], 0
	}

	var minCount int = math.MaxInt32

	for i := 0; i < len(matrices)-1; i++ {
		formerMatrices := matrices[:i+1]
		latterMatrices := matrices[i+1:]
		matF, countF := calcMinMatrixChainMultiplication(formerMatrices, Range{0, i}, memo)
		matL, countL := calcMinMatrixChainMultiplication(latterMatrices, Range{i + 1, len(matrices) - 1}, memo)
		_, countFL := calcMultiplication(matF, matL)
		count := countF + countL + countFL
		if count < minCount {
			minCount = count
		}
	}
	memo[r] = minCount
	return Matrix{matrices[0].r, matrices[len(matrices)-1].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 <iostream>
#include <vector>
using namespace std;
typedef long long ll;

ll m[101][101];
vector<ll> p;

int main() {

    int n;
    cin >> n;
    ll a, b;
    for (int i = 0; i < n; i++) {
        cin >> a >> b;
        if (i == 0) 
            p.push_back(a);
        p.push_back(b);
    }

    for (int i = 0; i < n; i++) 
        m[i][i] = 0;
    // l: length
    for (int l = 1; l < n; l++) {
        for (int i = 0; i < n - l; i++) {
            int j = i + l;
            m[i][j] = (1 << 21);
            for (int k = i; k < j; k++) {
                ll q = m[i][k] + m[k+1][j] + p[i] * p[k+1] * p[j+1];
                
                if( q < m[i][j] )
                    m[i][j] = q;
            }
        }
    }

    cout << m[0][n-1] << '\n';
}

C++: #include <stdio.h>
#include <stdlib.h>
#include <stdlib.h>
#include <math.h>
#define MAX 100
void min(int,int);
int p[MAX]={},m[MAX][MAX]={},i,j,k;

void min(int n1,int n2){
  if(n1>n2) n2=n1;
}
    
int main()
{
  int n,r,l;

  scanf("%d",&n);

  for(i=1;i<=n;i++){
    scanf("%d %d",&p[i-1],&p[i]);
  }

  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);
      for(k=i;k<=j-1;k++){
	min(m[i][j],m[i][k]+m[k+1][j]+p[i-1]*p[k]*p[j]);
      }
    }
  }

  printf("%d\n",m[l][n]);

  return 0;
}

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

int n;
int r[101],c[101];
long long int dp[101][101];
int null = -1;
long long int ans;
long long int inf = 1<<24;
long long int dfs(int i,int j){
    long long int res=inf;
    if(dp[i][j] != null){
        return dp[i][j];
    }
    else if(i == j){
        res = 0;
    }
    else{
        for(int k=i;k<j;k++){
            res = min(dfs(i,k) + dfs(k+1,j) + r[i]*c[k]*c[j],res);
        }
    }

    dp[i][j] = res;
    //cout << i << " " << j << " " << dp[i][j] << endl;
    return res;
}

int main(){
    cin >> n;
    for(int i=0;i<n;i++){
        cin >> r[i] >> c[i];
    }
    for(int i=0;i<=n;i++){
        for(int j=0;j<=n;j++){
            dp[i][j] = null;
        }
    }
    ans = dfs(0,n-1);
    cout << ans << endl;
    return 0;

}

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

const int INF = 1e9;

int N;
vector<int> R, C;
vector<vector<int> > dp;

int dfs(int l, int r) {
  if ( r == l ) return 0;
  if ( dp[l][r] ) return dp[l][r];

  int ret = INF;
  for ( int i = l; i < r; i++ ) {
    ret = min(ret, dfs(l, i)+dfs(i+1, r)+R[l]*C[i]*C[r]);
  }
  
  return dp[l][r] = ret;
}

int main() {  
  cin >> N;

  R = vector<int>(N);
  C = vector<int>(N);
  for ( int i = 0; i < N; i++ ) {
    cin >> R[i] >> C[i];
  }

  dp = vector<vector<int> >(N, vector<int>(N, 0));

  cout << dfs(0, N-1) << endl;
  
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n)   FOR(i,0,n)
#define pb emplace_back
typedef long long ll;
typedef pair<int,int> pint;

int dp[102][102],p[102];
const int INF=1000100010;
int main(){
    int n,l,r;
    cin>>n;
    rep(i,n){
        cin>>l>>r;
        if(i!=n-1) p[i]=l;
        else p[i]=l,p[i+1]=r;
    }
    FOR(i,1,n+1)FOR(j,1,n+1){
        if(i!=j)dp[i][j]=INF;
        else dp[i][j]=0;
    }
    FOR(i,1,n+1)FOR(l,1,n-i+1)FOR(r,l+1,i+l+1){
        dp[l][i+l]=min(dp[l][i+l],dp[l][r-1]+dp[r][i+l]+p[l-1]*p[r-1]*p[l+i]);
    }
    cout<<dp[1][n]<<endl;
    return 0;
}

C++: #include <iostream>
#include <string>
#include <algorithm>
#include <stdio.h>
#include <memory.h>
using namespace std;

struct matrix {
	int row;
	int col;
};
int main()
{
	int N;
	scanf("%d", &N);
	matrix vec[100];
	memset(vec, 0, sizeof(vec));
	for (int i = 0; i < N; ++i) {
		scanf("%d %d", &vec[i].row, &vec[i].col);
		//cin >> vec[i].row >> vec[i].col;
	}
	//vector<vector<int>> dp(N, vector<int>(N));
	int dp[100][100];
	memset(dp, 0, sizeof(dp));
	for (int len = 1; len < N; ++len) {
		for (int i = 0; i + len < N; ++i) {
			int j = i + len;
			dp[i][j] = 2147483647;
			for (int k = i; k < i + len; ++k) {
				dp[i][j] = min(dp[i][k] + dp[k + 1][j] + vec[i].row * vec[k].col * vec[j].col, dp[i][j]);
			}
		}
	}
	printf("%d\n", dp[0][N - 1]);
	//cout << dp[0][N - 1] <<endl;
	return 0;
}

C++: // http://algorithms.blog55.fc2.com/blog-entry-66.html

#include <iostream>
using namespace std;
#include <stdio.h>
#include <string.h>

#define M 100

int N,R[M+1],C[M][M],B[M][M];

void compute(){
	int i=0,j,k,cost;
	memset(C,99,sizeof(C));
	for(;i<N;i++)C[i][i]=0;
	for(j=1;j<N;j++)
		for(i=0;i<N - j; i++ ){
			for (k = i; k < i + j; k++ ){
				cost = C[i][k] + C[k+1][i+j] + R[i]*R[k+1]*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 >> N;
	int z,i=0;
	for (; i < N; i++ ) cin >> R[i]>>z;
	R[i]=z;
	//SIZE++;
}

void output(){
	cout <<  C[0][N-1] << endl;
	//order(0, N);
	//cout << endl;
}

main(){
	input();
	compute();
	output();
}

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];  //??´?????????????¬¬i??????????????????p[i-1]*p[i]??????m[i][j]???????????????i??°j??????????????????????§£
    cin>>n;
    for(int i=0;i<n;i++)
        cin>>p[i]>>p[i+1];

    //init
    for(int i=1;i<=n;i++) m[i][i]=0;
    for(int l=2;l<=n;l++) //?????????2????????????????§???????????????´????????°?????????n
    {
        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++)
            {
                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]<<endl;
}