MTrap DP chain matrix

#include<stdio.h>
typedef long long int ll;

ll arr[210];

ll min(ll a,ll b){
    return (a < b ? a : b);
}

ll dp[210][210];

ll cal(int L,int R){
    if(L == R){
        return 0;
    }
    if(dp[L][R] != -1)return dp[L][R];

    ll mina = 1e18;
    for(int m = L ; m < R ; m ++){
        mina = min(mina , cal(L,m) + cal(m+1,R) + (arr[L-1] * arr[m] * arr[R]));
    }
//  printf("Test (%d,%d) : %lld\n",L,R,mina);
    return dp[L][R] = mina;
}

int main()
{
    for(int i = 0 ; i < 210 ; i ++)for(int j = 0 ; j < 210 ; j ++)dp[i][j] = -1;
    int n;
    scanf("%d",&n);
    for(int i = 0 ; i < n -1 ; i ++){
        ll x;
        scanf("%lld %lld",&arr[i],&x);
    }
    scanf("%lld %lld",&arr[n-1],&arr[n]);

    printf("%lld",cal(1,n));
    return 0;
}