Go: package main

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

const (
	initialBufSize = 100000
	maxBufSize     = 1000000
)

var sc *bufio.Scanner

func initScanner(r io.Reader) *bufio.Scanner {
	buf := make([]byte, initialBufSize)

	sc := bufio.NewScanner(r)
	sc.Buffer(buf, maxBufSize)
	sc.Split(bufio.ScanWords) // bufio.ScanLines
	return sc
}

func main() {
	sc = initScanner(os.Stdin)
	fmt.Println(resolve(parseProblem()))
}

type matrixSize struct{ row, col int }

func calcNum(i, j matrixSize) int {
	return i.row * j.col * i.col
}

func parseProblem() (int, []matrixSize) {
	n := scanInt(sc)
	sizes := make([]matrixSize, n)
	for i := 0; i < n; i++ {
		sizes[i] = matrixSize{row: scanInt(sc), col: scanInt(sc)}
	}
	return n, sizes
}

var dp [][]int

func initDP(n int) {
	dp = make([][]int, n+1)
	for i := 0; i < len(dp); i++ {
		dp[i] = make([]int, n+1)
		for j := 0; j < len(dp[i]); j++ {
			dp[i][j] = math.MaxInt64
		}
	}
}

func resolve(n int, sizes []matrixSize) int {
	// TODO 復習
	initDP(n)
	_rec(sizes, 0, n)
	return dp[0][n]
}

func _rec(sizes []matrixSize, l, r int) int {
	if dp[l][r] != math.MaxInt64 {
		return dp[l][r]
	}
	if r-l <= 1 {
		dp[l][r] = 0
		return 0
	}
	num := math.MaxInt64
	for i := l + 1; i < r; i++ {
		v := _rec(sizes, l, i) + _rec(sizes, i, r) + calcNum(matrixSize{sizes[l].row, sizes[i].row}, matrixSize{sizes[i].row, sizes[r-1].col})
		if v < num {
			num = v
		}
	}
	dp[l][r] = num
	return dp[l][r]
}

// snip-scan-funcs
func scanInt(sc *bufio.Scanner) int {
	sc.Scan()
	i, _ := strconv.Atoi(sc.Text())
	return int(i)
}
func scanString(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

C++: #include <climits>
#include <iomanip>
#include <iostream>
#include <utility>
#include <vector>

using namespace std;

int main() {
    int n;
    cin >> n;
    vector<pair<int, int>> m(n);
    for (int i = 0; i < n; ++i) {
        int a, b;
        cin >> a >> b;
        m[i] = make_pair(a, b);
    }

    vector<vector<int>> v(n, vector<int>(n, INT_MAX));
    for (int i = 0; i < n; ++i)
        v[i][i] = 0;

    for (int width = 2; width <= n; ++width) {
        for (int i = 0; i < n - width + 1; ++i) {
            int j = i + width - 1;
            for (int k = i; k < j; ++k) {
                v[i][j] =
                    min(v[i][j], v[i][k] + v[k + 1][j] +
                                     m[i].first * m[k].second * m[j].second);
            }
        }
    }
    cout << v[0][n - 1] << '\n';
}

C++: #include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define FOR(i,a,b) for(ll i=a;i<=b;i++)
#define FORD(i,a,b) for(int i=a;i>=b;i--)
#define ALL(a)  (a).begin(),(a).end()
#define SZ(a) int((a).size())
#define SORT(c) sort((c).begin(),(c).end())
#define MEMSET(v, h) memset((v), h, sizeof(v))
#define sqr(x) ((x) * (x))
#define bit(n) (1LL<<(n))
#define pcnt(x) __builtin_popcountll(x)
#define PB push_back
#define MP make_pair
#define endl "\n"
using Edge = pair<int,int>;
using Graph = vector<vector<Edge>>;
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; }
// ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
// ll lcm(ll a,ll b){return a/gcd(a,b)*b;}

ll dp[110][110];
const ll MAX = 1001001001001001;

int main() {
  int n; cin >> n;
  ll p[n+1];
  FOR(i,0,n-1){
    cin >> p[i] >> p[i+1];
  }
  FOR(i,1,n){
    FOR(j,1,n){
      if(i==j) continue;
      else dp[i][j] = MAX;
    }
  }
  
  FOR(l,2,n){
    FOR(i,1,n-l+1){ //連鎖長がlのものでループ
      int j = i+l-1;
      FOR(k,i,j-1){
        ll q = dp[i][k] + dp[k+1][j] + p[i-1]*p[k]*p[j];
        chmin(dp[i][j],q);
      }
    }
  }
  cout << dp[1][n] << "\n";

}

C++: // -*- mode:c++; coding:utf-8; c-basic-offset:2; -*-
// ALDS1_10_B: Matrix Chain Multiplication

#include <algorithm>
#include <climits>
#include <cstdio>

using uint = unsigned int;

static uint matrix_chain_multiplication(const uint p[], const uint n)
{
  uint m[n][n];
  for (auto i = 0u; i < n; ++i) m[i][i] = 0u;

  for (auto d = 1u; d < n; ++d) {
    for (auto i = 0u, j = i+d; j < n; ++i, ++j) {
      auto min = UINT_MAX;
      for (auto k = i; k < j; ++k) {
        // min(Mi..j = (Mi..k) * (Mk+1..j)
        //           = (Mi..k) + (Mk+1..j) + p[i]*p[k+1]*p[j+1])
        auto cost = m[i][k] + m[k+1][j] + p[i]*p[k+1]*p[j+1];
        min = std::min(min, cost);
      }
      m[i][j] = min;
    }
  }
  return m[0][n-1];
}

int main()
{
  uint n;
  std::scanf("%u", &n);
  uint p[n+1];
  for (auto i = 0u; i < n; ++i) {
    std::scanf("%u %u", &p[i], &p[i+1]);
  }
  auto c = matrix_chain_multiplication(p, n);
  std::printf("%u\n", c);
}

// eof

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

#define ASC(vec) vec.begin(), vec.end()		// 昇順ソート 例：sort(ASC(vec));
#define DESC(vec) vec.rbegin(), vec.rend()	// 降順ソート 例:sort(DESC(vec));
#define rep(i, n) for(int i = 0; i < (n); i++)
#define Rep(i, n) for(int i = 1; i < n; i++)

const int mod = 1000000007;
const int inf = (int)1e9 + 7;
const long long INF = 1LL << 60;

using ii = pair<int, int>;
using ll = long long;
using vi = vector<int>;
using vd = vector<double>;
using vb = vector<bool>;
using vl = vector<ll>;
using vs = vector<string>;
using vvi = vector<vector<int>>;
using vvl = vector<vector<ll>>;
using vvb = vector<vector<bool>>;
using vii = vector<pair<int, int>>;

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

ll GCD(ll a, ll b) { return b ? GCD(b, a % b) : a; }
ll LCM(ll a, ll b) { return (a * b) / GCD(a, b); }
int round_int(int a, int b) { return (a + (b - 1)) / b; }

// 素因数分解; 返り値は(素数, 乗数)のvector配列
vector<pair<ll, int>> factorize(ll n) {
	vector<pair<ll, int>> res;
	for (ll i = 2; i * i <= n; ++i) {
		if (n % i) continue;
		res.emplace_back(i, 0);
		while (n % i == 0) {
			n /= i;
			res.back().second++;
		}
	}
	if (n != 1) res.emplace_back(n, 1);
	return res;
}

constexpr array<int, 9> dx = { 0, 1, 0, -1, -1, 1, 1, -1, 0 };
constexpr array<int, 9> dy = { 1, 0, -1, 0, 1, 1, -1, -1, 0 };
//constexpr auto MAX = 100000;

// ──────────────────────────────────────────────────────────────────


#define N 101

int dp[N + 1][N + 1], p[N + 1];

int main() {
    int n;

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

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

    return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(obj) (obj).begin(),(obj).end()
typedef long long ll;
ll mod=2e12;
ll cnt=0;
#define nil -1
int p[200];
int c[200][200];

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n;cin>>n;
    for(int i=1;i<=n;i++) cin>>p[i-1]>>p[i];
    for(int i=0;i<=n;i++)c[i][i]=0;
    for(int l=2;l<=n;l++){
      for(int i=1;i<=n-l+1;i++){
        int j=i+l-1;
        c[i][j]=(1<<21);
        for(int k=i;k<=j-1;k++){
          c[i][j]=min(c[i][j],c[i][k]+c[k+1][j]+p[i-1]*p[k]*p[j]);
        }
      }
    }
    cout<<c[1][n]<<endl;
   return 0;
}