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 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[0].r, matrices[len(matrices)-1].c}, v
	}
	if len(matrices) == 0 {
		panic("must not be empty")
	} else if len(matrices) == 1 {
		return matrices[0], 0
	} else if len(matrices) == 2 {
		return calcMultiplication(matrices[0], matrices[1])
	}

	var minCount int = math.MaxInt32

	for i := 0; i < len(matrices)-1; i++ {
		formerMatrices := matrices[:i+1]
		latterMatrices := matrices[i+1:]
		matF, countF := calcMinMatrixChainMultiplication(formerMatrices, Range{0, i}, memo)
		matL, countL := calcMinMatrixChainMultiplication(latterMatrices, Range{i + 1, len(matrices) - 1}, memo)
		_, countFL := calcMultiplication(matF, matL)
		count := countF + countL + countFL
		if count < minCount {
			minCount = count
		}
	}
	return Matrix{matrices[0].r, matrices[len(matrices)-1].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())
}

Python: #!/usr/bin/env python
from __future__ import division, print_function
from sys import stdin


def main():
    num_mat = int(stdin.readline())
    r = [int(s) for s in stdin.readline().split()]
    for _ in range(num_mat-1):
        _, row = (int(s) for s in stdin.readline().split())
        r.append(row)

    if num_mat < 2:
        print(0)
        return
    elif num_mat < 3:
        print(r[0]*r[1]*r[2])
        return

    M = []
    M.append([0] * num_mat)
    M.append([r[i]*r[i+1]*r[i+2] for i in range(len(M[-1])-1)])

    for i in range(2, num_mat):
        N = []
        for j in range(num_mat-i):
            N.append(min(M[k][j]+M[i-1-k][1+j+k]+r[j]*r[1+j+k]*r[i+1+j]
                         for k in range(i)))
        M.append(N)
    print(M[-1][0])


main()

Python: # https://onlinejudge.u-aizu.ac.jp/courses/lesson/1/ALDS1/10/ALDS1_10_B
# 普通に難しい
# アイデアは写真の解説を参照

# データの入力
N = int(input())

for i in range(N):
    if i == 0:
        P = list(map(int, input().split()))
        continue
    P.append(int(input().split()[1]))

# dpテーブルの用意 minを取るときはinf埋めしておくと処理が楽になるしバグが見つかりやすい
INF = 2**32-1
dp = [[INF]*N for _ in range(N)]

# dpテーブルの初期化
# 対角成分0
for ij in range(N):
    dp[ij][ij] = 0

# dpの更新 どう更新しているのか、なんでこう更新するのかは写真を参照
for l in range(1, N):  # lは対角成分からいくつ離れているか (なん個行列をかけるかという解釈も可)
    for i in range(N):
        j = i+l
        if j >= N:
            continue
        for k in range(i, j):
            dp[i][j] = min(dp[i][k] + dp[k+1][j] + P[i]
                           * P[j+1]*P[k+1], dp[i][j])
# from pprint import pprint
# pprint(dp)
print(dp[0][-1])

Python: import sys
sys.setrecursionlimit(10**7)
debug = False

def dprint(*objects):
    if debug == True:
        print(*objects)

# n = int(input())
# a, b = map(int, input().split())
# int_list = list(map(int, input().split()))
# l = list(input().split())



def solve():
    n = int(input())
    mat_list = []
    for i in range(n):
        mat_list.append(list(map(int, input().split())))
    dprint(mat_list)

    # 掛け始めのidxと掛け終わりのidxをi, jとし、計算回数を持つメモ
    memo = [[0 for i in range(n)] for i in range(n)]

    def calc(start, end):
        dprint("*", start, end)
        # 1つの行列なら0
        if end == start:
            return 0

        # メモがあれば返す
        if memo[start][end] != 0:
            return memo[start][end]

        # 2つの行列なら、答えを計算しメモ追記
        if end - start == 1:
            cost = mat_list[start][0] * mat_list[start][1] * mat_list[end][1]
            memo[start][end] = cost
            dprint(start, end, cost)
            return cost

        # 3つ以上なら、再帰
        min_cost = -1
        if end - start >= 2:
            for right_start in range(start+1, end+1):
                left = calc(start, right_start-1)
                right = calc(right_start, end)
                cost = left + right + mat_list[start][0] * mat_list[right_start][0] * mat_list[end][1]
                if min_cost == -1 or min_cost > cost:
                    min_cost = cost
                dprint(start, end, right_start, min_cost, cost)

        memo[start][end] = min_cost
        return min_cost

    ans = calc(0, n-1)
    dprint(memo)
    print(int(ans))

solve()

Python: N = int(input())

P = []
for i in range(N):
    if i == 0:
        P = list(map(int, input().split()))
        continue
    P.append(int(input().split()[1]))

dp = [[float("inf")]*N for _ in range(N)]

for i in range(N):
    dp[i][i] = 0

for l in range(1, N):  
    for i in range(N):
        j = i+l
        if j < N:
            for k in range(i, j): 
                dp[i][j] = min(dp[i][k] + dp[k+1][j] + P[i]*P[j+1]*P[k+1], dp[i][j])

print(dp[0][-1])

Python: N = int(input())
R = [0]*N
C = [0]*N
for i in range(N):
    R[i], C[i] = map(int, input().split())

INF = 10**18
dp = [[INF]*N for i in range(N)]
for i in range(N):
    dp[i][i] = 0
for l in range(1, N):
    for i in range(N-l):
        a0 = R[i]
        c0 = C[i+l]
        dp[i][i+l] = min(a0*C[j]*c0 + dp[i][j] + dp[j+1][i+l] for j in range(i, i+l))
print(dp[0][N-1])

Python: import sys

n = int(sys.stdin.readline())

m = list(map(int, sys.stdin.readline().split()))
for _ in range(n-1):
    _, a = sys.stdin.readline().split()
    m.append(int(a))

c = [[-1 for _ in range(n)] for _ in range(n)]

def val(a, b):
    if a==b: return 0
    if c[a][b]>0: return c[a][b]
    c[a][b]=val(a+1,b)+m[a-1]*m[a]*m[b]
    for k in range(a+1, b):
        v=val(a,k)+val(k+1,b)+m[a-1]*m[k]*m[b]
        if c[a][b]>v: c[a][b]=v
    return c[a][b]

print(val(0, n-1))

Python: def least_multiplication(mtx):
    N = len(mtx)
    mul = [[None] * N for x in range(N)]

    for i in range(N):
        mul[i][i] = 0
    #pprint.pprint(mul)

    for chain in range(1, N):
        for begin in range(N-chain):
            end = begin + chain
            cand = []
            for j in range(begin, end):
                left = mul[begin][j]
                down = mul[j+1][end]
                this = mtx[begin][0] * mtx[j][1] * mtx[end][1]
                cand.append(left + down + this)
            mul[begin][begin+chain] = min(cand)
        #pprint.pprint(mul)
    return mul[0][N-1]


def main():
    n = int(input())
    matrices = []
    for i in range(n):
        col, row = map(int, input().split())
        matrices .append((col, row))
    ans = least_multiplication(matrices)
    print(ans)


main()

Python: import sys

sys.setrecursionlimit(10**7)

inf = float('inf')

def solve():
    n = int(sys.stdin.readline())

    r = [0] * n
    c = [0] * n

    for i in range(n):
        ri, ci = map(int, sys.stdin.readline().split())
        r[i] = ri
        c[i] = ci

    dp = [[0]*(n + 1) for i in range(n + 1)]

    for ls in range(2, n + 1):
        for i in range(n - ls + 1):
            dp[i][i + ls] = inf
            for j in range(i + 1, i + ls):
                dp[i][i + ls] = min(dp[i][i + ls], dp[i][j] + dp[j][i + ls] + r[i]*r[j]*c[i + ls - 1])

    ans = dp[0][n]

    print(ans)

if __name__ == '__main__':
    solve()