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 (r Range) length() int {
	return r.end - r.start + 1
}

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

	var minCount int = math.MaxInt32

	for i := 0; i < r.length()-1; i++ {
		formerRange := Range{r.start, r.start + i}
		latterRange := Range{r.start + i + 1, r.end}
		matF, countF := calcMinMatrixChainMultiplication(matrices, formerRange, memo)
		matL, countL := calcMinMatrixChainMultiplication(matrices, latterRange, memo)
		_, countFL := calcMultiplication(matF, matL)
		count := countF + countL + countFL
		if count < minCount {
			minCount = count
		}
	}
	memo[r] = minCount
	return Matrix{matrices[r.start].r, matrices[r.end].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 <utility>
using namespace std;

#define REP(i, n) for(int i = 0; i < (n); i++)

typedef pair<int, int> pii;

const int N_SIZE = 100;

int dp[N_SIZE + 1][N_SIZE + 1];

void solve(int n, pii rc[])
{
  REP(i, n)
    dp[i][i] = rc[i].first * rc[i].second;
  REP(i, n - 1)
    dp[i][i + 1] = dp[i][i] * rc[i + 1].second;
  for(int i = 2; i < n; i++){
    for(int j = 0, k = i + j, m = 100000000; k < n; j++, k++){
      for(int l = j, x; l < k; l++){
	x = ((j == l) ? dp[j][l] * rc[k].second : dp[j][l]) + ((l + 1 == k) ? dp[l + 1][k] * rc[j].first : dp[l + 1][k]);
	if(j != l && l + 1 != k)
	  x += rc[j].first * rc[l].second * rc[k].second;
	m = min(m, x);
      }
      dp[j][k] = m;
      m = 100000000;
    }
  }
}
 
int main()
{
  int n;
  cin >> n;
  pii rc[n];
  REP(i, n)
    cin >> rc[i].first >> rc[i].second;
  solve(n, rc);
  cout << dp[0][n - 1] << endl;
}

C++: #include <iostream>
#include <cstdio>
#include <cstring>
#include <climits>
#include <string>
#include <algorithm>
#include <cmath>
#include <vector>
#include <stack>
#include <queue>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <sstream>
#include <numeric>

// namespace
using namespace std;

// int mcm(const vector<int> &p, int i, int j) { // i-th matrix has the size (p[i], p[i+1])
//     if (i == j) return 0;
//     int m = INT_MAX;
//     for (int k = i; k < j; ++k) {
//         m = min(m, mcm(p, i, k) + mcm(p, k + 1, j) + p[i] * p[k + 1] * p[j + 1]);
//     }
//     return m;
// }

// int mcm(const vector<int> &p, int i, int j, vector<vector<int>> &dp) { // i-th matrix has the size (p[i], p[i+1])
//     if (i == j) return 0;
//     if (dp[i][j] < INT_MAX) return dp[i][j];
//     int m = INT_MAX;
//     for (int k = i; k < j; ++k) {
//         m = min(m, mcm(p, i, k, dp) + mcm(p, k + 1, j, dp) + p[i] * p[k + 1] * p[j + 1]);
//     }
//     return dp[i][j] = m;
// }

int mcm(const vector<int> &p) { // i-th matrix has the size (p[i], p[i+1])
    int n = p.size() - 1;
    vector<vector<int>> dp(n, vector<int>(n, INT_MAX));
    for (int i = 0 ; i < n; ++i) dp[i][i] = 0;
    for (int l = 1; l < n; ++l)
        for (int i = 0, j; (j = i + l) < n; ++i)
            for (int k = i; k < j; ++k)
                dp[i][j] = min(dp[i][j], dp[i][k] + dp[k + 1][j] + p[i] * p[k + 1] * p[j + 1]);
    return dp[0][n-1];
}

int main() {
    int n, r, c;
    cin >> n;
    vector<int> p;
    for (int i = 0; i < n; ++i) {
        cin >> r >> c;
        p.push_back(r);
    }
    p.push_back(c);
    auto ans = mcm(p);
    cout << ans << endl;
    return 0;
}

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 ( 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] + p[i - 1] * p[k] * p[j]);
               }
          }
     }
     cout << m[1][n] << endl;

     return 0;
}

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

#include <stdio.h>
#include <string.h>

#define M 100
int R[M+1],C[M][M],B[M][M];
void D(int i,int j){
	if(i==j)printf("M%d",i);
	else printf("("),D(i,B[i][j]-1),D(B[i][j],j),printf(")");
}

main(){
	int N,i=0,j,k,c;
	scanf("%d",&N);
	for(;i<N;i++)scanf("%d%d",R+i,&c);
	R[i]=c;
	memset(C,99,sizeof(C));
	for(i=0;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++)
		if((c=C[i][k]+C[k+1][i+j]+R[i]*R[k+1]*R[i+j+1])<C[i][i+j])C[i][i+j]=c,B[i][i+j]=k;
	printf("%d\n",C[0][N-1]);
	//order(0,N);
	//puts("");
}

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

static const int N = 100;

int main(){
    int n,a[N + 1],b[N + 1][N + 1],k;
    cin >> n;
    for(int i = 1;i <= n;i++){
        cin >> a[i - 1] >> a[i];
    }
    for(int i = 1;i <= n;i++){
        b[i][i] = 0;
    }
    for(int i = 2;i <= n;i++){
        for(int j = 1;j <= n - i + 1;j++){
            k = j + i - 1;
            b[j][k] = (1 << 21);
            for(int l = j;l <= k - 1;l++){
                b[j][k] = min(b[j][k],b[j][l] + b[l + 1][k] + a[j - 1]*a[l]*a[k]);
            }
        }
    }
    cout << b[1][n] << endl;
    return 0;
}

C++: #include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<cmath>

#define FOR(i,a,b) for(int i=(a);i<(b);++(i))
#define REP(i,n) FOR(i,0,n)

#define dump(x) cerr << #x << " = " <<(x)<<endl;
#define debug(x) cerr << #x << " = " <<(x) << "(L" << __LINE__ << ")" << __FILE__ << endl;

using namespace std;

int main(void){
  int n,i;
  cin >> n;
  vector<int> input(n+1);
  REP(i,n) cin >> input[i] >> input[i+1];
  
  vector<vector<int>> res(n+1, vector<int>(n+1));
  vector<int> p(n+1);
  FOR(i,1,n+1) res[i][i]=0;
  FOR(l,2,n+1){
    FOR(i,1,n-l+2){
      int j = i+l-1;
      res[i][j] = (1<<21);
      FOR(k,i,j){
        res[i][j] = min(res[i][j],res[i][k]+res[k+1][j] + input[i-1]*input[k]*input[j]);

        
      }
    }
  }
  /*
  REP(i,n+1){
    REP(j,n+1){
      cout << res[i][j] << " ";
    }
    cout << endl;
  }
  */
  cout << res[1][n] << endl;


  return 0;
}

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=0;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-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]<<endl;

  return 0;
}