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++: //
//  main.cpp
//  ALDS1_10_B:MatrixChainMultiplication
//
//  Created by Kang on 2020/8/14.
//  Copyright © 2020 Kang. All rights reserved.
//

#include <cstdio>
using namespace std;

int main(int argc, const char * argv[]) {
    int n;
    int p[101];       // 矩阵维数
    int dp[101][101]; // 只用上三角
    
    scanf("%d", &n);
    for (int i = 0; i < n; i++) {
        scanf("%d%d", &p[i], &p[i+1]);
    }
    // j-i = dif, dif = 0, 1, ..., n - 1
    for (int dif = 0; dif < n; dif++) {     // dif = j - i;
        for (int i = 1; i <= n-dif; i++) {  // i表示行数
            if(dif == 0) {dp[i][i] = 0;}
            else {
                int min = ~(1 << 31);
                int tmp;
                for (int k = i; k < i + dif; k++) {
                    tmp = dp[i][k] + dp[k + 1][i+dif] + p[i-1] * p[k] * p[i + dif];
                   /*printf("dp[%d][%d] + dp[%d][%d] + p[%d] * p[%d] * p[%d] = %d\n",
                          i, k, k+1, i+dif, i-1, k, i+dif, tmp);*/
                    if (tmp < min) min = tmp;
                }
                dp[i][i+dif] = min;
                
                // printf("dp[%d][%d] = %d\n",i, i+dif, min);
                // printf("--------------------\n");
            }
        }
    }
    printf("%d\n", dp[1][n]);
    
    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=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++: #include <iostream>
#include <iomanip>
#include <utility>
#include <cmath>
#include <random>
#include <vector>
#include <map>
#include <set>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <algorithm>
using namespace std;

#define rep(i,n) for(int i = 0; i<n; ++i)
#define REP(i,n) for(int i = 1; i<=n; ++i)
#define all(x) begin(x),end(x)
#define show(obj) {for(auto x:obj)cout<<x<<' ';cout<<endl;}
typedef long long ll;
typedef pair<int,int> ip;
typedef pair<ll,ll> lp;
const int inf = 1001001000;
const ll INF = 1LL<<60;
const int MOD = (int)1e9 + 7;

template<class T> inline bool chmin(T& a, T b) {if (a > b) { a = b; return true; } return false;}

int main(){
	int N; cin>>N;
	vector<ip> M(N);
	rep(i,N)cin>>M[i].first>>M[i].second;
	vector<vector<int>> dp(N,vector<int>(N,inf));
	rep(i,N)dp[i][i] = 0;
	for(int i = 1; i<N; ++i){
		int l = 0, r = i;
		for(int j = 0; j<N-i; ++j){
			for(int k = l; k<r; ++k){
				chmin(dp[l][r], dp[l][k] + dp[k+1][r] + M[l].first * M[k].second * M[r].second);
				// chmin(dp[l][r], dp[l][r-1] + M[l].first * M[r].first * M[r].second);
			}
			// printf("[l,r] => [%d,%d]\n",l,r);
			++l; ++r;
		}
	}
	cout<<dp[0][N-1]<<endl;
	return 0;
}

C++: #include<iostream>
#include<algorithm>
using namespace std;

int nlist[110];
int dp[110][110];

int main(){
  int n;
  cin>>n;
  for(int i=0;i<n;i++){
    cin>>nlist[i]>>nlist[i+1];
  }
  for(int i=1;i<n;i++){
    for(int j=0;j<n-i;j++){
      dp[j][j+i]=1<<30;
      for(int k=0;k<i;k++){
	dp[j][j+i]=min(dp[j][j+i],dp[j][j+k]+dp[j+k+1][j+i]+nlist[j]*nlist[j+k+1]*nlist[j+i+1]);
      }
    }
  }
  cout<<dp[0][n-1]<<endl;
  return 0;
}

C++: #include "bits/stdc++.h"
using namespace std;
typedef long long ll;
// #define int long long

template <class T>
bool INRANGE(T x, T a, T b) { return a <= x && x <= b; }

#define REP(i, n) for (int i = 0; i < (n); ++i)
#define RREP(i, n) for (int i = (n); i >= 0; --i)
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define RFOR(i, a, b) for (int i = (a); i >= (b); --i)
#define ALL(v) (v).begin(), (v).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" \
                      << " " << __FILE__ << endl;
#define DUMP(list) cout << "{ "; for(auto nth : list){ cout << nth << " "; } cout << "}" << endl;
typedef vector<int> vi;
typedef vector<string> vs;
typedef vector<vi> vvi;
typedef pair<int, int> pii;

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

    int n;
    cin >> n;

    vi p(102);
    REP(i, n) cin >> p[i] >> p[i+1];
    vvi dp(102, vi(102, 0));

    FOR(l, 2, n+1){           // 対象とする行列の数
        FOR(i, 1, n-l+2){     
            int j = i + l - 1;   
            dp[i][j] = (1 << 20); // dp[i][j] := [Mi, Mj]の最小回数
            FOR(k, i, j){
	            dp[i][j] = min(dp[i][j], dp[i][k] + dp[k+1][j] + p[i-1] * p[k] * p[j]);
            }
        }
    }

  cout << dp[1][n] << endl;

    
}