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<bits/stdc++.h>
using namespace std;
#define INF 1000000000
#define mp make_pair
#define fi first
#define se second

int main()
{
    int n;cin >> n;
    vector<pair<int,int>> matrix(n);
    int a,b;
    for (int i=0;i<n;i++)
    {
        cin >> a >> b;
        matrix[i]=mp(a,b);
    }
    vector<vector<pair<int,pair<int,int>>>> dp(n,vector<pair<int,pair<int,int>>> (n,mp(INF,mp(-1,-1))));
    for (int i=0;i<n;i++)
    {
        dp[i][i].fi=0;
        dp[i][i].se.fi=matrix[i].fi;
        dp[i][i].se.se=matrix[i].se;
    }
    for (int len=1;len<n;len++)
    {
        for (int l=0;l<n-len;l++)
        {
            int r=l+len;
            //cout << l << r << endl;
            for (int m=l;m<r;m++)
            {
                if (dp[l][r].fi>dp[l][m].fi+dp[m+1][r].fi+dp[l][m].se.fi*dp[l][m].se.se*dp[m+1][r].se.se)
                {
                    //cout << l <<" " << r << ":" ;
                    dp[l][r].fi=dp[l][m].fi+dp[m+1][r].fi+dp[l][m].se.fi*dp[l][m].se.se*dp[m+1][r].se.se;
                    dp[l][r].se.fi=dp[l][m].se.fi;
                    dp[l][r].se.se=dp[m+1][r].se.se;
                    //cout << dp[l][r].fi<< endl;
                }
            }
        }
    }
    cout << dp[0][n-1].fi << endl;
    return 0;
}

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

constexpr int INF = 1e9;

int dp[110][110];

int main(){
  int n; cin >> n;
  int p[110];
  for( int i = 0; i < n; i++ ) cin >> p[i] >> p[i + 1];
  for( int i = 0; i < 110; i++ ){
    for( int j = 0; j < 110; j++ ){
      if( i != j ) dp[i][j] = INF;
    }
  }
  
  for( int l = 2; l <= n; l++ ){
    for( int i = 0; i < n - l + 1; i++ ){
      int j = l + i - 1;
      for( int k = i; k < j; k++ ){
	dp[i][j] = min( dp[i][j], dp[i][k] + dp[k + 1][j] + p[i] * p[k + 1] * p[j + 1] );
      }
    }
  }

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

C++: #include<iostream>
#include<algorithm>
using namespace std;
#define INF 1<<30

static const int N = 100;

int main() {
    int n;
    int 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] = INF;
            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 <bits/stdc++.h>
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<algorithm>
using namespace std;
#define 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[i][k] + m[k + 1][j] + p[i - 1] * p[k] * p[j]);
			}
		}
	}
	cout << m[1][n] << endl;
	return 0;
}

C++: #include <stdio.h>
#include <stdint.h>
#include <iostream>
#include <fstream>
#include <cassert>
#include <climits>
using namespace std;

#define DEBUG (0)

#if DEBUG
#define DPRINTF(...) do { \
    printf("D(L%d) %s: ", __LINE__, __func__); \
    printf(__VA_ARGS__); \
  } while (false)
#else
#define DPRINTF(...)
#endif // DEBUG


struct Matrix {
  int numOfRow;
  int numOfColumn;
};


struct MinMatrix {
  int minMultiply;
  int numOfRow;
  int numOfColumn;
};


const int kMaxSize = 100;
const int kInvalid = -1;
MinMatrix minArrays[kMaxSize][kMaxSize];


bool isValid(MinMatrix mtx)
{
  return mtx.minMultiply != kInvalid ? true : false;
}

MinMatrix getMinScalarMultiply(const Matrix matrices[], int start, int end)
{
  DPRINTF("start %d  end %d\n", start, end);

  assert(start <= end);

  if (isValid(minArrays[start][end]))
    return minArrays[start][end];

  if (start + 1 == end)
  {
    MinMatrix mtx;

    mtx.minMultiply = 0;
    mtx.numOfRow = matrices[start].numOfRow;
    mtx.numOfColumn = matrices[start].numOfColumn;

    minArrays[start][end] = mtx;

    return minArrays[start][end];
  }


  MinMatrix minMtx;
  minMtx.minMultiply = INT_MAX;

  for (int i = start + 1; i < end; i++)
  {
    MinMatrix mtx0 = getMinScalarMultiply(matrices, start, i);
    MinMatrix mtx1 = getMinScalarMultiply(matrices, i, end);

    MinMatrix mtx;

    mtx.minMultiply = mtx0.minMultiply + mtx1.minMultiply + mtx0.numOfRow * mtx0.numOfColumn * mtx1.numOfColumn;
    mtx.numOfRow = mtx0.numOfRow;
    mtx.numOfColumn = mtx1.numOfColumn;

#if DEBUG
    DPRINTF("start %d  end %d  i %d : mtx.minMultiply %d  min.minMultiply %d\n",
        start, end, i, mtx.minMultiply, minMtx.minMultiply);
    DPRINTF("  mtx0.minMultiply %d  mtx1.minMultiply %d\n",
        mtx0.minMultiply, mtx1.minMultiply);
#endif

    if (minMtx.minMultiply > mtx.minMultiply)
      minMtx = mtx;
  }

  DPRINTF("start %d  end %d  multiply %d\n", start, end, minMtx.minMultiply);

  minArrays[start][end] = minMtx;

  return minArrays[start][end];
}


int calcMinScalarMultiply(const Matrix matrices[], int num)
{
  if (num <= 1)
    return 0;

  MinMatrix mtx = getMinScalarMultiply(matrices, 0, num);

  return mtx.minMultiply;
}


int main() {

  // init
  for (int i = 0; i < kMaxSize; i++)
    for (int j = 0; j < kMaxSize; j++)
      minArrays[i][j].minMultiply = kInvalid;

  int numOfMatrix;
  cin >> numOfMatrix; cin.ignore();

  Matrix  matrices[numOfMatrix];
  for (int i = 0; i < numOfMatrix; i++)
  {
    cin >> matrices[i].numOfRow; cin >> matrices[i].numOfColumn; cin.ignore();
  }

#if DEBUG
  for (int i = 0; i < numOfMatrix; i++)
  {
    DPRINTF("Matrix %d: %d %d\n", i, matrices[i].numOfRow, matrices[i].numOfColumn);
  }
#endif

  cout << calcMinScalarMultiply(matrices, numOfMatrix) << endl;

  return 0;
}