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
	} else if len(matrices) == 2 {
		return calcMultiplication(matrices[0], matrices[1])
	}

	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
		}
	}
	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 <map>
#include <set>
#include <list>
#include <cmath>
#include <queue>
#include <stack>
#include <cstdio>
#include <string>
#include <vector>
#include <complex>
#include <cstdlib>
#include <cstring>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <functional>

#define mp       make_pair
#define pb       push_back
#define all(x)   (x).begin(),(x).end()
#define rep(i,n) for(int i=0;i<(n);i++)
#define repi(i,a,b) for(int i = (a); i < (b); i++)

using namespace std;

typedef    long long          ll;
typedef    unsigned long long ull;
typedef    vector<bool>       vb;
typedef    vector<int>        vi;
typedef    vector<vb>         vvb;
typedef    vector<vi>         vvi;
typedef    pair<int,int>      pii;

const int INF=1<<29;
const double EPS=1e-9;

const int dx[]={1,0,-1,0},dy[]={0,-1,0,1};
int n;//計算する行列の数
const int MAX_N =110;
int dp[MAX_N][MAX_N];//dp[i][j]:=Ai...Ajの計算に必要な最小のコスト
pii A[MAX_N];//行列firstを行secondを列とする。
int B[MAX_N+1][MAX_N+1]; //B[i][j]:=Ai...Ajに最適な括弧を挿入する場所
void init(){
	for(int i =0; i < n;i++){
		for(int j = 0;j < n;j++){
			dp[i][j]=INF;
			B[i][j]=0;
		}
	}
	for(int i =0;i < n;i++){
		dp[i][i]=0;
	}
}
//計算
int solve(){
	for(int k =1;k <n;k++){//個数
		for(int i =0;i <n-k;i++){//何処から始めるか
			for(int j =i;j <i+k;j++){//何処で終わるか
				int sz =A[i].first*A[j].second*A[i+k].second;
				int cost=dp[i][j]+dp[j+1][i+k]+sz;
				if(dp[i][i+k] >cost){
					dp[i][i+k]=cost;
					B[i][i+k]= j+1;//括弧を挿入する場所
				}

			}
		}
	}
	return dp[0][n-1];
}
//復元
void order(int i,int j){
	if(i==j){
		cout <<'A'<<i;
	}else{
		cout <<"(";
		order(i, B[i][j]-1);
		order(B[i][j], j);
		cout <<")";
	}
}

int main(){
	cin>>n;
	init();
	for(int i =0;i < n;i++){
		cin>>A[i].first>>A[i].second;
	}
	cout <<solve()<<endl;
	//order(0, n-1);
	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < (n) ; i++)
#define rrep(i,n) for(int i = n-1; i >= 0 ; i--)
constexpr auto INF = 2147483647;
typedef long long ll;

// void DebugGrid(int row, int column, auto table){
//   cout << endl;
//   rep(i,row){
//     rep(j,column) cout << table[i][j] << " ";
//     cout << endl;
//   }
// }

int main(){

  ll ans, n, DP[100][100];
  vector<pair<int,int>> matrix;
  cin >> n;
  rep(i,n){
    pair<int,int> inp;
    cin >> inp.first >> inp.second;
    matrix.emplace_back(inp);
  }

  rep(i,n)rep(j,n) DP[i][j] = INF;
  for(int l=0; l<n; l++)for(int i=0; i<n-l; i++){
    if(l == 0) DP[i][i] = 0;
    else{
      for(int j=i;j<=i+l;j++){
      DP[i][i+l] = min(DP[i][i+l],DP[i][j]+DP[j+1][i+l] + (matrix[i].first*matrix[j].second*matrix[i+l].second));
      }
    }
  }

  // DebugGrid(n,n,DP);
  cout << DP[0][n-1] << endl;
  return 0;
}

C++: #include <iostream>
#include <iomanip>
#include <vector>
#include <set>
#include <string>
#include <queue>
#include <algorithm>
#include <map>
#include <cmath>
#include <numeric>
#include <list>
#include <stack>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <tuple>

#define rep(i, n) for (int i = 0; i < (n); i++)
#define rep1(i, n) for (int i = 1; i <= (n); i++)
#define show(a, n) rep(i,n) {cout<<a[i]<<' ';} cout<<endl;

using namespace std;
typedef vector<int> vi;
typedef pair<int, int> pii;
typedef long long ll;
typedef vector<ll> vll;
typedef pair<long long, long long> pll;

const int INF = 1 << 30;
const long long INFL = 1LL << 62;
const int MOD = 1000000007;
const int MAX = 100000;
const int N = 100010;

struct mat {
	ll r, c;
};

int main() {
//	cout << fixed << setprecision(15);
	int n;
	cin >> n;
	vector<mat> m(n);
	rep(i, n) cin >> m[i].r >> m[i].c;

	if(n == 1) {cout << 0 << endl; return 0; }

	vector<vll> dp(n, vll(n));
	rep(i, n) dp[i][i] = 0;
	int l, r;
	for(int d = 1; d <= n - 1; d++) {
		for(l = 0; l + d < n; l++) {
			r = l + d;
			dp[l][r] = INFL;
			for(int k = l; k + 1 <= r; k++) {
				dp[l][r] = min(dp[l][k] + dp[k + 1][r] + m[l].r * m[k].c * m[r].c, dp[l][r]);
			}
		}
	}
	cout << dp[0][n - 1] << endl;
}

C++: #include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define repr(i, n) for (int i = (n); i >= 0; --i)
#define FOR(i, m, n) for (int i = (m); i < (n); ++i)
#define FORR(i, m, n) for (int i = (m); i >= (n); --i)
using namespace std;
typedef long long ll;
const ll mod = 1000000007;
const ll mod2 = 998244353;
const int INF = (1<<21);

int main() {
  int n;
  cin >> n;
  int cnt[n][n];
  int p[n+1];
  rep(i, n) {
    cin >> p[i] >> p[i+1];
  }

  rep(i, n) {
    rep(j, n) {
      if (i == j) cnt[i][j] = 0;
      else cnt[i][j] = INF;
    }
  }

  FOR(l, 1, n) {
    rep(i, n-l) {
      int j = i+l;
      FOR(k, i, j) {
        cnt[i][j] = min(cnt[i][j], cnt[i][k] + cnt[k+1][j] + p[i] * p[k+1] * p[j+1]);
      }
    }
  }

  cout << cnt[0][n-1] << endl;



  
  return 0;
}

C++: #include <bits/stdc++.h>
#define N 110
using namespace std;
int A[N];
int dp[N][N];

int Min(int &a,int b){return a = min(a,b);}
int main(){
  int n;
  cin>>n;

  for(int i=0,cnt=0;i<n;i++){
    int a,b;
    cin>>a>>b;
    if(i == 0) A[cnt++] = a;
    A[cnt++] = b;
  }

  for(int i=0;i<N;i++){
    for(int j=0;j<N;j++)dp[i][j] = 1e9;
    dp[i][i] = 0;
  }
  
  for(int len=0;len<n;len++)
    for(int l=1;l<n;l++){
      int r = l+len;
      for(int m = l;m<r;m++){
        Min(dp[l][r],dp[l][m] + dp[m+1][r] + A[l-1]*A[m]*A[r]);
      }
}
  
  cout<<dp[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];

	scanf("%d", &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]);
				}
			}
		}

		printf("%d\n", m[1][n]);

		return 0;
	}