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<bits/stdc++.h>
using namespace std;
#define N 100
#define INF 1<<25
int n,p[N+1],m[N+1][N+1];
int matrixchainmultiplication(){
  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]=INF;
      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]);
      }
    }
  }
  return m[1][n];
}
int main(){
  cin>>n;
  for(int i=0;i<n;i++) cin>>p[i]>>p[i+1];
  cout<<matrixchainmultiplication()<<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++){
      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++: #include<iostream>
#include<algorithm>
#define MAX 100
#define INFTY (1 << 21)
using namespace std;

int main() {
	int n, p[MAX + 1], mat[MAX + 1][MAX + 1];;
	cin >> n;
	for (int i = 1; i <= n; i++) {
		cin >> p[i - 1] >> p[i];
	}
	for (int i = 1; i <= n; i++) {
		mat[i][i] = 0;
	}
	for (int k = 2; k <= n; k++) {
		for (int i = 1; i <= n - k + 1; i++) {
			int j = i + k - 1;
			mat[i][j] = INFTY;
			for (int h = i; h <= j - 1; h++) {
				mat[i][j] = min(mat[i][j], mat[i][h] + mat[i][h] + mat[h + 1][j] + (p[i - 1] * p[h] * p[j]));
			}
		}
	}
	cout << mat[1][n] << endl;
	char c;
	cin >> c;
	return 0;
}

C++: //#include <bits/stdc++.h>
#include <iostream>
#include <algorithm>

using namespace std;
int N = 100;

int main(){
  int i,j,k,l;
  int n,p[N+1],m[N+1][N+1];
  cin >> n;
  for(i = 1; i <= n; i++){
    cin >> p[i-1];
    cin >> 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++){
        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++: //	created : 16/03/13
// 	author   : Rp7rf
#include <iostream>
#include <vector>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <set>
typedef long long ll;
typedef unsigned long long ull;
using namespace std;
#define rep(i,a) for(int i = 0 ; i < a ; i ++)
#define loop(i,a,b) for(int i = a ; i < b ; i ++)
#define vi vector<int>
#define mp make_pair
#define pb push_back
#define MOD 1000000007
#define INF 1e9
static const int N = 100;

int main(void){
	int n, p[N+1], m[N+1][N+1];
	cin>>n;
	rep(i,n+1){
		cin>>p[i]>>p[i+1];
	}
	
    loop(i,1,n+2)m[i][i] = 0;
 
    loop(l,2,n+1){
        loop(i,1,n-l+2){
            int j = i + l - 1;
            m[i][j] = (1<<21);
            loop(k,i,j){
                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;
}

C++: #include <bits/stdc++.h>
#ifdef _DEBUG
#include "debug.hpp"
#else
#define debug(...)
#endif
#define REP(i, m, n) for(int (i) = (m); (i) < (n); ++i)
#define rep(i, n) REP(i, 0, n)
using namespace std;
typedef long long ll;
typedef pair<ll, ll> P;
const int INF = 1e9 + 7;
const ll LINF = 1LL << 60;
template<class T, class U> inline bool chmax(T &a, const U &b) { if(a < b) { a = b; return true; } return false; }
template<class T, class U> inline bool chmin(T &a, const U &b) { if(a > b) { a = b; return true; } return false; }

ll dp[110][110];

int main() {
  cin.tie(0); ios::sync_with_stdio(false);
  int n;
  cin >> n;
  vector<int> rw(n), cl(n);
  rep(i,n) cin >> rw[i] >> cl[i];
  rep(i,110) rep(j,110) dp[i][j] = LINF;
  rep(i,110) dp[i][i] = 0;
  REP(i,1,n+1) rep(l,n) {
    int r = l+i;
    if(r >= n) continue;
    REP(j,l,r) {
      chmin(dp[l][r], dp[l][j]+dp[j+1][r]+rw[l]*cl[j]*cl[r]);
    }
  }
  cout << dp[0][n-1] << '\n';
  return 0;
}

C++: #include "stdafx.h"
#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 (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;
}

C++: //全くわからんので解き方を見てみる
//行列dpを作って、dp[i][j]はi~jのかけ算をした際の最小の回数
//これを順に計算すれば確かに最小のものは出そう

#include<iostream>
#include<vector>
#include<utility>
#include<algorithm>

using namespace std;

int main(){
  int INF=1000000000;
  int n;cin >> n;
  vector< vector<int> > dp(n,vector<int>(n,INF));
  //vector< vector< pair<int,int> > > x(n,vector< pair<int,int> >(n,make_pair(0,0)));
  vector< pair<int,int> > m(n);
  for(int i=0;i<n;i++){
    int r,c;cin >> r >> c;
    m[i]=make_pair(r,c);
  }

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

  for(int l=0;l<n;l++){//長さのループ
    for(int i=0;i<n-l;i++){//行のループ
      if(l==0){dp[i][i+l]=0;}
      for(int j=i;j<i+l;j++){//更新のループ(d[i][i+l])
        dp[i][i+l]=min({dp[i][i+l],dp[i][j]+dp[j+1][i+l]+m[i].first*m[j].second*m[i+l].second});
      }
    }

  }
  /*
  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;

}