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 <iomanip>
#include <vector>
#include <algorithm>
#include <cstring>
#include <map>
#include <queue>
#include <cmath>
#include <complex> // complex<double> a(1.2 , 2.3);// real(): 1.2, imag()2.3
using namespace std;

#define MOD 1000000007
#define ll long long
#define ld long double
#define FOR(i,a,b) for(ll i=(ll)a;i<(ll)b;i++)
#define rep(i,n) FOR(i,0,n)
#define pb push_back
#define mp make_pair
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define rmsame(a) sort(all(a)),a.erase(unique(all(a)), a.end())
#define rmvector(a,b) rep(i,a.size())rep(j,b.size())if(a[i]==b[j]){a.erase(a.begin()+i);i--;break;}
#define first_more_idx(ve, num) upper_bound(all(ve), num)-ve.begin() // idx = first_more_idx(ve,num); if(idx = ve.size()) , then not exist
#define first_lessequal_idx(ve, num) lower_bound(all(ve), num)-ve.begin()
#define pq_pair_tB priority_queue <pair<ll,ll>, vector<pair<ll,ll> > , greater<pair<ll,ll> > >
#define pq_pair_ts priority_queue <pair<ll,ll> > // only sort first param
template<typename X> bool exist(vector<X> vec, X item){return find(all(vec), item)!=vec.end();}
ll gcd(ll a, ll b){if(b==0)return a;return gcd(b,a%b);}
ll lcm(ll a, ll b){return a/gcd(a,b)*b;}
ll power(ll x, ll n){if(n == 0) return 1;return  (n%2)? x*power(x, n-1)%MOD : power(x*x%MOD, n/2);}
ll dx[]={0, 0, -1, 1};
ll dy[]={1, -1, 0, 0};// up,down,left right

ll N ;
vector<pair<ll,ll> > num;
ll dp[105][105];

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    

    cin >> N ;

    rep(i, N){
        ll a,b ;
        cin >> a >> b;

        num.pb(mp(a,b));
    }

    rep(i, N){
        dp[i][i] = 0;
    }
    
    rep(distance, N){
        rep(i, N){
            if(distance == 0){
                dp[i][i] = 0;
                continue;
            }
            
            ll from = i; ll to = i + distance;
            if(to >= N) continue;
            dp[from][to] = 1e13;
            for(int j = from; j <= to; j++){
                dp[from][to] = min(dp[from][to],
                                   dp[from][j] + dp[j+1][to] + num[from].first * num[j].second * num[to].second);
                                   
            }
        }
    }
    cout << dp[0][N-1] << endl;

    
    //cout << fixed << setprecision(16) << ans << endl;
    return 0;
}

C++: #include <bits/stdc++.h>
#define r(i,n) for(int i=0;i<n;i++)
#define int long long
using namespace std;
int dp[111][111],n,L[111],R[111];

int dfs(int l,int r){
	if(dp[l][r]!=-1)return dp[l][r];
	if(l==r)return dp[l][r]=0;
	int res=1e17;
	for(int i=l;i<r;i++){
		res=min(res,dfs(l,i)+dfs(i+1,r)+L[l]*R[i]*R[r]);
	}
	return dp[l][r]=res;
}

signed main(){
	memset(dp,-1,sizeof(dp));
	cin>>n;
	r(i,n)cin>>L[i]>>R[i];
	dfs(0,n-1);
	cout<<dp[0][n-1]<<endl;
}

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

typedef long long ll;
typedef pair<ll, ll> P;

#define pb push_back
#define rep(i, n) for(int i = 0; i < (n); i++)
#define FOR(i, a, n) for(int i = a; i < (n); i++)
#define mod (ll)(1e9+7)
#define int ll

__attribute__((constructor))
void initial() {
  cin.tie(0);
  ios::sync_with_stdio(false);
}

signed main() {
	int n, p[101], m[101][101];
  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;
}