Go: package main

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

type Matrix struct {
	r int // num of row
	c int // num of column
}

type Range struct {
	start int // index, inclusive
	end   int // index, inclusive
}

func (r Range) length() int {
	return r.end - r.start + 1
}

func calcMultiplication(x, y Matrix) (Matrix, int) {
	if x.c != y.r {
		panic("cannnot calculate")
	}
	return Matrix{x.r, y.c}, x.r * y.c * x.c
}

func calcMinMatrixChainMultiplication(matrices []Matrix, r Range, memo map[Range]int) (Matrix, int) {
	if v, ok := memo[r]; ok {
		return Matrix{matrices[r.start].r, matrices[r.end].c}, v
	}
	if r.length() == 0 {
		panic("must not be empty")
	} else if r.length() == 1 {
		return matrices[r.start], 0
	}

	var minCount int = math.MaxInt32

	for i := 0; i < r.length()-1; i++ {
		formerRange := Range{r.start, r.start + i}
		latterRange := Range{r.start + i + 1, r.end}
		matF, countF := calcMinMatrixChainMultiplication(matrices, formerRange, memo)
		matL, countL := calcMinMatrixChainMultiplication(matrices, latterRange, memo)
		_, countFL := calcMultiplication(matF, matL)
		count := countF + countL + countFL
		if count < minCount {
			minCount = count
		}
	}
	memo[r] = minCount
	return Matrix{matrices[r.start].r, matrices[r.end].c}, minCount
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	n, _ := nextInt(sc)
	matrices := make([]Matrix, n)
	for i := 0; i < n; i++ {
		r, _ := nextInt(sc)
		c, _ := nextInt(sc)
		matrices[i] = Matrix{r, c}
	}
	memo := make(map[Range]int)
	_, resultCount := calcMinMatrixChainMultiplication(matrices, Range{0, len(matrices) - 1}, memo)
	fmt.Println(resultCount)
}

func nextInt(sc *bufio.Scanner) (int, error) {
	sc.Scan()
	return strconv.Atoi(sc.Text())
}

C++: #include <stdio.h>
#include <algorithm>
using namespace std;

typedef long long ll;
#define INF ((ll)10000000000)
#define MAX_N (110)
typedef struct {
    ll r;
    ll c;
} Mat;

int n;
Mat M[MAX_N];
ll dp[MAX_N][MAX_N];

ll dfs(int i, int j)
{
    if ( j - i == 1 ) return 0;
    else if ( dp[i][j] ) return dp[i][j];
    else {
	ll ret = INF;
	for ( int k = i + 1; k < j; k++ ) {
	    ret = min(ret, dfs(i, k) + dfs(k, j) + M[i].r * M[k].r * M[j-1].c );
	}

	return dp[i][j] = ret;
    }
}

int main()
{
    scanf("%d", &n);

    for ( int i = 0; i < n; i++ ) {
	scanf("%lld %lld", &M[i].r, &M[i].c);
    }
    
    ll ans = dfs( 0, n );
    printf("%lld\n", ans);

    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++: //matrix chain multiplication
#include<iostream>
#include<cstdio>
#include<cstdlib> //malloc
using namespace std;
#define INF 1000000001
int DP[100][100];
int *p;
int rec(int r, int c) { //what to record on DP, r番目の行列からc番目の行列まで掛け算
    int Min = INF;
    for (int i = 0; i < c - r; i++) { //どこで区切るか
        Min = min(Min, DP[r][r+i] + DP[r+i+1][c] + p[r-1]*p[r+i]*p[c]);
        //3項目は2つのDPをつなぐ計算量
    }
    return Min;
}
int main() {
    int N;
    cin >> N;
    for (int i = 1; i <= N; i++) { //matrix starts index 1, p[] starts index 0
        for (int j = 1; j <= N; j++) {
            DP[i][j] = 0;
        }
    }
    p = (int *)malloc(sizeof(int) *(N+1) ); //main()外でp使うから面倒だけど
    //N+1 -> 0 start, 最後の行列の列 p[N]
    for (int i = 0; i < N; i++) {
        cin >> p[i]; cin >> p[i+1]; //start p[2]
    }
    for (int i = 1; i < N; i++) DP[i][i+1] = p[i-1]*p[i]*p[i+1]; //2つの積
    
    int y;
    for (int k = 0; k <= N - 2; k++) {
        for (int x = 1; x <= N - 2; x++) {
            y = x+(2+k);
            if (x <= N && y <= N) DP[x][y] = rec(x, y);
        }
    }
    
    cout << DP[1][N] << endl; //最初の行列から最後の行列まで
    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++: //Matrix Chain Multiplication
#include <iostream>
#include <climits>

using namespace std;

int matrixChainMultiplication(int p[], int n) {
    int m[n + 1][n + 1];
    for(int i = 0; i < n + 1; i++) m[i][i] = 0;
    for(int l = 2; l < n + 1; l++) {
        for(int i = 1; i < n - l + 2; i++) {
            int j = i + l - 1;
            m[i][j] = INT_MAX;
            for(int k = i + 1; k < j + 1; k++) {
                m[i][j] = min(m[i][j], m[i][k - 1] + m[k][j] + p[i - 1] * p[k - 1] * p[j]);
            }
        }
    }
    return m[1][n];
}

int main() {
    int n, r, c;
    cin >> n;
    int p[n + 1];
    for(int i = 0; i < n; i++) {
        cin >> r >>  c;
        if(i == 0) p[0] = r;
        p[i + 1] = c;
    }

    cout << matrixChainMultiplication(p, n) << endl;
}

C++: #include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
int main() {
    int n,p[110],dp[101][101];
    cin >> n;
    for (int i = 1;i <= n;i++) {
        cin >> p[i - 1] >> p[i];
        dp[i][i] = 0;
    }
    for (int l = 2; l <= n;l++) {
        for (int i = 1;i <= n - l + 1;i++) {
            int j = i + l - 1;
            dp[i][j] = (1 << 21);
            for (int k = i; k <= j - 1;k++) {
                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;
}

C++: #include<stdio.h>
#include<math.h>

static int N=100;

int main(){

  int n,p[N+1],m[N+1][N+1];
  int i,j,l,k;
  
  scanf("%d",&n);

  for(i=1;i<=n;i++){
    scanf("%d",&p[i-1]);
    scanf("%d",&p[i]);
  }

  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;

      for(k=i;k<=j-1;k++){
	m[i][j] = fmin(m[i][j],m[i][k]+m[k+1][j]+p[i-1]*p[k]*p[j]);
      
	  }
    }
  }

  printf("%d",m[1][n]);
  printf("\n");

  return 0;
}