Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

//util
var sc = bufio.NewScanner(os.Stdin)

func nextStr() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

func printList(list []int) {
	buf := bufio.NewWriter(os.Stdout)
	for _, v := range list {
		buf.Write([]byte(fmt.Sprintf(" %d", v)))
	}
	buf.Write([]byte("\n"))
	buf.Flush()
}

//solve
//単純な場合
func matrixChainMultiplication() {
	//行列が1つだけのとき
	for i := 1; i <= n; i++ {
		m[i][i] = 0
	}
	for l := 2; l <= n; l++ {
		for i := 1; i <= n-l+1; i++ {
			j := i + l - 1
			m[i][j] = 1 << 21
			//kまでで区切る
			for 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])
			}
		}
	}
}

func max(a, b int) int {
	if a > b {
		return a
	} else {
		return b
	}
}

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

const MAX = 100

var n int
var p [MAX + 1]int

//m[i][j]: Mi * Mi+1 * ... * Mjを計算するときに必要なスカラー乗算の最小回数
var m [MAX + 1][MAX + 1]int

func main() {
	sc.Split(bufio.ScanWords)
	n = nextInt()
	for i := 1; i <= n; i++ {

		p[i-1] = nextInt() //行数
		p[i] = nextInt()   //列数
	}

	matrixChainMultiplication()
	fmt.Println(m[1][n])
}

C++: #include<iostream>
#include<algorithm>
#include<string>

using namespace std;

static const int N = 100;
static const int INF = (1 << 21);

int main() {
    int n;
    int p[N + 1];
    int m[N + 1][N + 1];

    cin >> n;

    for (int i = 0; i < n; i++) {
        cin >> p[i] >> p[i + 1];
    }

    for (int i = 0; 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] = INF;
            for (int k = i; k <= j; 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 <bits/stdc++.h>
using namespace std;
#define int long long
const int INF = 1e9;

signed main(){
  int N; cin >> N;
  vector<vector<int> > dp(N + 1, vector<int> (N + 1, 0));
  vector<int> r(N + 1);
  for(int i = 1; i <= N; i++) cin >> r[i - 1] >> r[i];
  for(int l = 1; l < N; l++){
    for(int i = 1; i <= N - l; i++){
      int j = l + i;
      dp[i][j] = INF;
      for(int k = i; k < j; k++){
        dp[i][j] = min(dp[i][j], dp[i][k] + dp[k + 1][j] + r[i - 1] * r[k] * r[j]);
      }
    }
  }
  cout << dp[1][N] << endl;
}

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

const int MAX = 1 << 30;

struct Matrix {
  Matrix(int r,int c){
    row = r;
    col = c;
  }
  int row,col;
};

int dp[100][100];

int rec(int left, int right, vector<Matrix>& M)
{
  if(left==right){ return 0; }
  
  if(dp[left][right]<MAX){ return dp[left][right]; }
  
  if(right-left==1){
    dp[left][right] = M[left].row * M[left].col * M[right].col;
    return dp[left][right];
  }
  
  int answer = MAX;
  for(int mid=left;mid<right;mid++){
    //////////////
    //int a = rec(left,mid,M)+rec(mid+1,right,M) + M[mid].row * M[mid].col * M[mid+1].col;
    //cout << "left:" << left << ",mid:" << mid << ",right:" << right << ",answer:" << a << endl;
    //////////////
    answer = min(answer,rec(left,mid,M)+rec(mid+1,right,M) + M[left].row * M[mid].col * M[right].col);
  }
  
  dp[left][right] = answer;
  return dp[left][right];
}


int main(void){
    // Your code here!
    int n;
    cin >> n;
    
    if(n==1){
      cout << 0 << endl;
      return 0;
    }
    
    vector<Matrix> M;
    for(int i=0;i<n;i++){
      int row,col;
      cin >> row >> col;
      M.push_back(Matrix(row,col));
    }
    
    for(int i=0;i<n;i++){
      for(int j=0;j<n;j++){
        dp[i][j] = MAX;
      }
    }
    
    rec(0,n-1,M);

    cout << dp[0][n-1] << endl;
}

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++: #define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
#define rep0(n) for (int i = 0; i < (int)(n); i++)
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep2(i, s, n) for (int i = s; i < (int)(n); i++)
#define rep3(i, s, n) for (int i = s; i > (int)(n); i--)
#define all(obj) obj.begin(), obj.end()
#define from1(obj) obj.begin() + 1, obj.end()
#define db(x) cerr << #x << ":" << x << " "
#define dbl(x) cerr << #x << ":" << x << "\n"
#define dbp(p) cerr << #p << ":(" << p.first << ", " << p.second << ") "
#define dbpl(p) cerr << #p << ":(" << p.first << ", " << p.second << ")\n"
#define dbt3(t3) cerr << #t3 << ":(" << get<0>(t3) << ", " << get<1>(t3) << ", " << get<2>(t3) << ") "
#define dbt3l(t3) cerr << #t3 << ":(" << get<0>(t3) << ", " << get<1>(t3) << ", " << get<2>(t3) << ")\n"
#define dbt4(t4) cerr << #t4 << ":(" << get<0>(t4) << ", " << get<1>(t4) << ", " << get<2>(t4) << ", " << get<3>(t4) << ") "
#define dbt4l(t4) cerr << #t4 << ":(" << get<0>(t4) << ", " << get<1>(t4) << ", " << get<2>(t4) << ", " << get<3>(t4) << ")\n"
#define dbv(vec) cerr << #vec << ":{ "; for (auto e : vec) cerr << e << ", "; cerr << "}\n"
#define dbvp(vec) cerr << #vec << ":{ "; for (auto p : vec) cerr << "(" << p.first << ", " << p.second << "), "; cerr << "}\n"
#define dbvv(vv) cerr << #vv << ":{\n"; for (auto vec : vv) { cerr << "{ "; for (auto e : vec) cerr << e << ", "; cerr << "}\n"; } cerr << "}\n"
#define dbm(map) cerr << #map << ":{ "; for (auto p : map) cerr << "(" << p.first << ", " << p.second << "), "; cerr << "}\n"
#define YN(f) cout << (f ? "YES" : "NO") << "\n"
#define Yn(f) cout << (f ? "Yes" : "No") << "\n"
#define yn(f) cout << (f ? "yes" : "no") << "\n"
using ll = long long;
using vi = vector<int>; using vl = vector<ll>; using vs = vector<string>; using vb = vector<bool>;
using vvi = vector<vi>; using vvl = vector<vl>; using vvb = vector<vb>;
using pii = pair<int, int>; using pil = pair<int, ll> ; using pll = pair<ll, ll>; using pli = pair<ll, int>;
using vpii = vector<pii>; using vpll = vector<pll>;
using ti3 = tuple<int, int, int>; using tl3 = tuple<ll, ll, ll>;
using ti4 = tuple<int, int, int, int>; using tl4 = tuple<ll, ll, ll, ll>;
using mii = map<int, int>; using mil = map<int, ll>; using mll = map<ll, ll>; using mli = map<ll, int>;

const int INF = 1e8;
vi r, c;
vvi dp; // dp[i][j]:Ai~Ajのスカラー乗算の最小回数

int rec(int i, int j) {
	if (dp[i][j] != INF) return dp[i][j];
	int res = INF;
	rep2(k, i, j)	res = min(res, rec(i, k) + rec(k + 1, j) + r[i] * c[k] * c[j]);
	return dp[i][j] = res;
}

int main() {	
	// 行列の番号は0-ind, 0 ~ n-1
	int n; cin >> n;
	r.assign(n, 0); c.assign(n, 0);
	rep(i, n) cin >> r[i] >> c[i];
	dp.assign(n, {}); rep(i, n) dp[i].assign(n, INF);
	rep(i, n) rep(j, i + 1) dp[i][j] = 0;
	rep(i, n - 1) dp[i][i + 1] = r[i] * c[i] * c[i + 1];
	// dbvv(dp);
	rec(0, n - 1);
	// dbvv(dp);
	cout << dp[0][n - 1] << endl;
}