Go: package main

/*
連鎖行列積
*/

import (
	"bufio"
	"bytes"
	"fmt"
	"log"
	"math"
	"os"
	"strconv"
	"strings"
)

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

type mem *[][]int

func main() {
	scanner := makeScanner(1024)
	n := eGetInt(scanner)
	p := make([]int, n+1)
	for i := 0; i < n; i++ {
		rowcol := eGetInts(scanner)
		p[i] = rowcol[0]
		p[i+1] = rowcol[1]
	}
	m := make([][]int, n)
	for i := 0; i < n; i++ {
		m[i] = make([]int, n)
	}
	// 初期値の格納
	for i := 0; i < n; i++ {
		for j := i; j < n; j++ {
			if i == j {
				m[i][j] = 0 //  同じ行列へのコストは当然0
			} else {
				m[i][j] = math.MaxInt64
			}
		}
	}

	// num : 行列の数. num == 1の場合は初期値0を格納ずみ
	for num := 2; num <= n; num++ {
		// s : スタート行列番号
		for s := 0; s+num <= n; s++ {
			// t : 終了行列番号
			t := s + num - 1
			// k : 仕切
			for k := s; k < t; k++ {
				m[s][t] = min(m[s][t], m[s][k]+m[k+1][t]+p[s]*p[k+1]*p[t+1])
			}
		}
	}
	fmt.Println(m[0][n-1])
}

////////////////////////////////////////////////////////////////////////////////
// ライブラリ
////////////////////////////////////////////////////////////////////////////////
func makeScanner(maxByte int) *bufio.Scanner {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Buffer(make([]uint8, 0, 8192), maxByte)
	return scanner
}
func makeWordScanner() *bufio.Scanner {
	scanner := makeScanner(8192)
	scanner.Split(bufio.ScanWords)
	return scanner
}
func eGetLine(r *bufio.Scanner) string {
	if r.Scan() {
		return r.Text()
	}
	err := r.Err()
	if err != nil {
		log.Fatal(err)
	}
	// EOF
	return ""
}
func eGetInt(r *bufio.Scanner) int {
	line := eGetLine(r)
	return eAtoi(line)
}
func eGetFields(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Fields(line)
}
func eGetInts(r *bufio.Scanner) []int {
	fields := eGetFields(r)
	ints := make([]int, len(fields))
	for i := 0; i < len(ints); i++ {
		ints[i] = eAtoi(fields[i])
	}
	return ints
}
func eGetChars(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Split(line, "")
}
func eAtoi(s string) int {
	n, err := strconv.Atoi(s)
	if err != nil {
		log.Fatal(err)
	}
	return n
}

type ints []int

func (s ints) String() string {
	var buf bytes.Buffer
	buf.WriteString("[")
	sep := ""
	for _, v := range s {
		buf.WriteString(fmt.Sprintf("%s%d", sep, v))
		sep = ", "
	}
	buf.WriteString("]")
	return buf.String()
}

func reverse(a ints) ints {
	r := make(ints, len(a))
	for i := 0; i < len(a); i++ {
		r[i] = a[len(a)-1-i]
	}
	return r
}
func max(a ints) (int, bool) {
	if len(a) == 0 {
		return 0, false
	}
	m := a[0]
	for _, e := range a {
		if e > m {
			m = e
		}
	}
	return m, true
}

// func min(a []int) int {
// 	m := a[0]
// 	for _, v := range a {
// 		if v < m {
// 			m = v
// 		}
// 	}
// 	return m
// }

func sum(a ints) int {
	if len(a) == 0 {
		return 0
	}
	sum := 0
	for _, e := range a {
		sum += e
	}
	return sum
}
func find(n int, a ints) int {
	for i, v := range a {
		if n == v {
			return i
		}
	}
	return -1
}

C++: /**
 * 	matrix chain multiplication
 * 	f(n,m) = multiply Mn*M(n+1)*...*M(m-1)*M(m)
 * 	f(n,n) = 1
 * 	r(n)=c(n-1)
 * 	f(n,n+1) = C(n) * R(n) * C(n+1) = c(n) * c(n-1) * c(n+1)
 * 	f(n,k,m) = f(n,k)*f(k+1,m)*C(n)*r(n)*c(k)
 * 	f(n,m) = min(f(n,k,m)
 */

#include <iostream>
#include <cmath>
#include <climits>

using namespace std;

int r[45] = {0};
int a[100][100] = {0};

int f(int n, int m);
int f(int n, int k, int m);


int f(int n, int k, int m)
{
	return f(n,k) + f(k+1,m) + (r[n] * r[k+1] * r[m+1]);
}

int f(int n, int m)
{
	if (n==m) return 0;
	int & ra = a[n][m];
	if (ra) return ra;
	ra = INT_MAX;
	for (int k=n;k<m;k++)
	{
		int ans = f(n,k,m);
		if (ans < ra) ra = ans;
	}
	return ra;
}

int main()
{
	int rr = 0;
	int cc = 0;
	int n = 0;
	cin >> n;
	for (int i=0;i<n;i++)
	{
		cin >> rr >> cc;
		r[i]=rr;
		r[i+1]=cc;
	}
	for (int i=0;i<n-1;i++)
	{
		a[i][i+1] = r[i] * r[i+1] * r[i+2];
	}
	int ans = f(0,n-1);
	cout << ans << endl;
}

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

#define rep(i, n) for(int i = 0; i < n; i++)
using namespace std;

typedef long long ll;

const int INF = 1 << 30;
const ll LLINF = 1LL << 62;

int mod = 1000000007;

int main(void){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    //A*Bの行列とB*Cの行列、計A*B*C回の乗算をしてA*Cの行列になる
    int N; cin >> N;
    int R[N], C[N]; rep(i, N) cin >> R[i] >> C[i];
    int dp[N+1][N+1];
    rep(i, N+1) rep(j, N+1) dp[i][j] = INF;
    rep(i, N+1) dp[i][i+1] = 0;
    for(int haba = 2; haba <= N; haba++){
        for(int left = 0; left < N; left++){
            int right = left + haba;
            if(right > N) break;
            for(int boarder = left+1; boarder <= right-1; boarder++){
                dp[left][right] = min(dp[left][right], dp[left][boarder] + dp[boarder][right] + R[left]*C[boarder-1]*C[right-1]);
            }
        }
    }

    cout << dp[0][N] << endl;
    return 0;
}

C++: #include<iostream>
#include<algorithm>
using namespace std;
#define INF (1 << 21)
int main(){

  //-------データの入力------------
  int n;
  cin >> n;
  int row[n];
  int column[n];
  for(int i = 0; i < n; i++){
    cin >> row[i] >> column[i];
  }
  //-----------------------------

  //[始点][終点（始点+幅）]の最小コスト
  int dp[n+1][n+1];

  //INFで初期化
  for(int i = 0; i < n; i++){
    for(int j = 0; j < n; j++){
      dp[i][j] = INF;
    }
  }

  //幅0はコスト0
  //dp[i][i+0] = 0
  for(int i = 0; i < n; i++){
    dp[i][i] = 0;
  }

  //幅:j = 0 から探索開始
  for(int j = 0; j <= n; j++){
    //始点: i
    for(int i = 0; i < n; i++){
      //仕切りを置く位置: k
      // (M_0, M_1, M_2, M_3) | (M_4, M_5)
      for(int k = i + 1; k <= i + j; k++){
        //現在のdp[i][i+j]より小さければ更新
        dp[i][i+j] = min(dp[i][i+j], dp[i][k-1] + dp[k][i+j] + row[i] * column[k-1] * column[i+j]);
      }
    }
  }
  /*
  for(int i = 0; i < n; i++){
    for(int j = 0; j < n; j++){
      cout << dp[i][j] << " ";
    }
    cout << endl;
  }
  */
  //始点０、幅n-1の最小コスト=> n個の行列の連鎖の計算に最低限必要な乗算の回数　を出力
  cout << dp[0][n-1] << endl;
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }

int n;
struct rcdata {
    int rr; int c;
};
vector<rcdata> m(110);
long long dp[110][110];

long long rec(int l, int r) {
    // cout << "l " << l << " r " << r << endl;
    if(dp[l][r] != 1e9) return dp[l][r];
    if(abs(l-r) <= 1) return dp[l][r] = 0;
    for(int mid = l+1; mid <= r-1; ++mid) {
        long long total = rec(l, mid)+rec(mid,r)+(m.at(l).rr*m.at(mid).rr*m.at(r-1).c);
        chmin(dp[l][r], total);
    }
    return dp[l][r];
}

int main() {
    cin >> n;
    for(int i = 0; i < n; ++i) {
        cin >> m.at(i).rr >> m.at(i).c;
    }

    for(int i = 0; i <= n; ++i) {
        for(int j = 0; j <= n; ++j) {
            dp[i][j] = 1e9;
        }
    }

    cout << rec(0, n) << endl;
}

C++: /**
 * 	matrix chain multiplication
 * 	f(n,m) = multiply Mn*M(n+1)*...*M(m-1)*M(m)
 * 	f(n,n) = 1
 * 	r(n)=c(n-1)
 * 	f(n,n+1) = C(n) * R(n) * C(n+1) = c(n) * c(n-1) * c(n+1)
 * 	f(n,k,m) = f(n,k)*f(k+1,m)*C(n)*r(n)*c(k)
 * 	f(n,m) = min(f(n,k,m)
 */

#include <iostream>
#include <cmath>
#include <climits>

using namespace std;

int r[45] = {0};
int a[100][100] = {0};

int f(int n, int m);
int f(int n, int k, int m);


int f(int n, int k, int m)
{
	return f(n,k) + f(k+1,m) + (r[n] * r[k+1] * r[m+1]);
}

int f(int n, int m)
{
	if (n==m) return 0;
	int & ra = a[n][m];
	if (ra) return ra;
	ra = INT_MAX;
	for (int k=n;k<m;k++)
	{
		int ans = f(n,k,m);
		if (ans < ra) ra = ans;
	}
	return ra;
}

int main()
{
	int rr = 0;
	int cc = 0;
	int n = 0;
	cin >> n;
	for (int i=0;i<n;i++)
	{
		cin >> rr >> cc;
		r[i]=rr;
		r[i+1]=cc;
	}
	for (int i=0;i<n-1;i++)
	{
		a[i][i+1] = r[i] * r[i+1] * r[i+2];
	}
	int ans = f(0,n-1);
	cout << ans << endl;
}