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++: #include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll INF = 1e18;
const ll mod = 1000000007;

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
template<class T> inline bool chmax(T& a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template<class T> inline bool chmin(T& a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
int ctoi(char c) {
  if (c >= '0' && c <= '9') {
    return c - '0';
  }
  return 0;
}
ll factorial(ll n) {
  if (n == 1) {
    return 1;
  }
  ll ans = factorial(n-1);
  return ans*n;
}
ll gcd(ll a, ll b) {
  if (a < b) {
    ll tmp = a;
    a = b;
    b = tmp;
  }
  ll r = a%b;
  while(r != 0) {
    a = b;
    b = r;
    r = a%b;
  }
  return b;
}
ll lcm(ll a, ll b) {
  return (a/gcd(a, b))*b;
}

int main() {
  ll n;
  cin >> n;
  vector <vector <ll>> dp(n, vector <ll> (n));
  vector <ll> v(n+1);
  rep(i, n) cin >> v.at(i) >> v.at(i+1);
  rep(i, n) dp.at(i).at(i) = 0;
  for (ll i = 2; i <= n; i++) {
    for (ll j =  0; i+j-1 < n; j++) {
      ll k = i+j-1;
      dp.at(j).at(k) = INF;
      for (ll l = j; l < k; l++) {
        dp.at(j).at(k) = min(dp.at(j).at(k), 
                             dp.at(j).at(l)+dp.at(l+1).at(k)+v.at(j)*v.at(l+1)*v.at(k+1));
      }
    }
  }
  cout << dp.at(0).at(n-1) << endl;
}

C++: #include <iostream>
#include <cstdlib>
#include <cstdio>

using namespace std;

typedef struct matrix{
  int row;
  int column;
  struct matrix *next;
  struct matrix *back; 
}Matrix;

Matrix *push_back(Matrix *begin, int row, int column) {
  Matrix *p = (Matrix*)malloc(sizeof(Matrix));
  p->row = row;
  p->column = column;
  p->next = NULL;
  p->back = NULL;
  if(begin == NULL) return p;
  Matrix *p2 = begin;
  while(p2->next != NULL) p2 = p2->next;
  p2->next = p;
  p->back = p2;
  return begin;
}

Matrix *product_count(Matrix *x, int type, int *count) {
  Matrix *a,*b;
  if(type == 0) {
    a = x->back;
    b = x;
  }
  else {
    a = x;
    b = a->next;
  }
  *count = 0;
  if(a == NULL || b == NULL) return x;
  *count += a->row * a->column * b->column;
  Matrix *c = (Matrix*)malloc(sizeof(Matrix));
  c->row = a->row;
  c->column = b->column;
  c->next = b->next;
  c->back = a->back;
  if(a->back != NULL) a->back->next = c;
  if(b->next != NULL) b->next->back = c;
  free(a);
  free(b);
  return c;
}

Matrix *product_atob(Matrix *a, Matrix *b, int type,  long *sum) {
  int count;
  if(a == b) return a;
  if(type == 0) {
    while(a->next != b) {
      b = product_count(b, 0, &count);
      *sum += count;
    }
  }
  else {
   while(a->next != b) {
      a = product_count(a, 1, &count);
      *sum += count;
    }
  }
  a = product_count(a, 1, &count);
  *sum += count;
  return a;
}

Matrix *solve(Matrix *x, long *sum) {
  if(x->next == NULL) return x;
  Matrix *min = x->next, *p = x;
  while (p->next != NULL) {
    p = p->next;
    if(min->column > p->column) min = p;
  }
  if(min->column < x->row) {
    x = product_atob(x, min, 0, sum);
    if(x->next != NULL) {
      p = solve(x->next,sum);
      x = product_atob(x,p,0,sum);
    }
  }
  else if(min->column > x->row) {
    if(x->back == NULL || x->back->row > x->row) {
      while(min->next != NULL) min = min->next;
      x = product_atob(x, min, 1, sum);
    }
    else{
      x = product_atob(x,min,1,sum);
    }
  }
  else {
    Matrix *min2 = x->next;
    p = x->next;
    while (p != min) {
      if(min2->column > min->column && min2->column > p->column) min2 = p;
      p = p->next;
    }
    x = product_atob(x, min2, 1, sum);
    product_atob(x->next, min, 0, sum);
    x = product_atob(x, x->next, 1, sum);
    if(x->next != NULL) {
      p = solve(x->next,sum);
      x = product_atob(x,p,0,sum);
    }
    p = solve(x,sum);
  }
  return x;
}

int main()
{
  int i,n,r,c;
  Matrix *begin = NULL;
  scanf("%d",&n);
  for (i = 0; i < n; i++) {
    scanf("%d %d",&r,&c);
    begin = push_back(begin,r,c);

  }
  long sum = 0;
  begin = solve(begin, &sum);
  cout << sum << endl;
  
  return 0;
}

C++: #include <stdio.h>
//https://www.geeksforgeeks.org/dynamic-programming-set-8-matrix-chain-multiplication/
//return the cost
/*int cal(int a[],int i, int j){
    if(i==j) return 0;
    int min = 1<<30;
    //printf("%d\n",min);
    for(int k = i; k<j; k++){
        int count = cal(a, i, k)+cal(a,k+1, j)+a[i-1]*a[k]*a[j];
        if(count<min) min = count;
    }
    
    return min;
}*/

int main()
{
    int n;
    scanf("%d",&n);
    int x[n+2], y[n+2];
    int dp[n+2][n+2];
    for(int i = 1; i<=n; i++){
        scanf("%d %d",&x[i],&y[i]);
        dp[i][i] = 0;
    } x[n+1] = y[n];
    dp[n+1][n+1] = 0;
    int min = 1<<30;
    for(int m = 2; m<=n+1; m++){
        for(int i = 2; i<=n+2-m ; i++){
            int j = i+m-1;
            dp[i][j] = 1<<30;
            for(int k = i; k<j; k++){
                int count = dp[i][k]+dp[k+1][j]+x[i-1]*x[k]*x[j];
                if(count<dp[i][j]) dp[i][j] = count;
            }
        }
        
    }
    
    //printf("%d\n",cal(x, 2,n+1));
    printf("%d\n",dp[2][n+1]);
    return 0;
}