Codeforces 706C Hard problem 2016-09-28 19:47 90人阅读 评论(0) 收藏

C. Hard problem

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

Vasiliy is fond of solving different tasks. Today he found one he wasn't able to solve himself, so he asks you to help.

Vasiliy is given n strings consisting of lowercase English letters. He wants them to be sorted in lexicographical order (as in the
dictionary), but he is not allowed to swap any of them. The only operation he is allowed to do is to reverse any of them (first character becomes last, second becomes one before last and so on).

To reverse the i-th string Vasiliy has to spent ci units
of energy. He is interested in the minimum amount of energy he has to spent in order to have strings sorted in lexicographical order.

String A is lexicographically smaller than string B if
it is shorter than B (|A| < |B|)
and is its prefix, or if none of them is a prefix of the other and at the first position where they differ character in A is smaller
than the character in B.

For the purpose of this problem, two equal strings nearby do not break the condition of sequence being sorted lexicographically.

Input

The first line of the input contains a single integer n (2 ≤ n ≤ 100 000) —
the number of strings.

The second line contains n integers ci (0 ≤ ci ≤ 109),
the i-th of them is equal to the amount of energy Vasiliy has to spent in order to reverse the i-th
string.

Then follow n lines, each containing a string consisting of lowercase English letters. The total length of these strings doesn't exceed100 000.

Output

If it is impossible to reverse some of the strings such that they will be located in lexicographical order, print  - 1. Otherwise, print the
minimum total amount of energy Vasiliy has to spent.

Examples

input

2
1 2
ba
ac

output

1

input

3
1 3 1
aa
ba
ac

output

1

input

2
5 5
bbb
aaa

output

-1

input

2
3 3
aaa
aa

output

-1

Note

In the second sample one has to reverse string 2 or string 3.
To amount of energy required to reverse the string 3 is smaller.

In the third sample, both strings do not change after reverse and they go in the wrong order, so the answer is  - 1.

In the fourth sample, both strings consists of characters 'a' only, but in the sorted order string "aa"
should go before string "aaa", thus the answer is  - 1.

题目的意思是给出n个字符串，要求通过逆置字符串的操作是所有字符串呈字典序，每次逆置消耗费用a[i]，问最小花费

每个字符串只有两个操作，变或不变，开2维数组记录花费即可；

#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <string>
#include <iostream>
using namespace std;
#define inf 0x3f3f3f3f

 long long dp[100005][2];
 int a[100005];
 string s[100005];
int n;

int main()
{
    while(~scanf("%d",&n))
    {
        for(int i=1;i<=n;i++)
        scanf("%d",&a[i]);
        for(int i=1;i<=n;i++)
        cin>>s[i];

        memset(dp,4557430888798830399,sizeof(dp));
        dp[0][0]=dp[0][1]=0;
        for(int i=1;i<=n;i++)
        {
            if(s[i]>=s[i-1])
            dp[i][0]=min(dp[i][0],dp[i-1][0]);
            reverse(s[i-1].begin(),s[i-1].end());

            if(s[i]>=s[i-1])
            dp[i][0]=min(dp[i][0],dp[i-1][1]);
            reverse(s[i-1].begin(),s[i-1].end());
            reverse(s[i].begin(),s[i].end());

            if(s[i]>=s[i-1])
            dp[i][1]=min(dp[i][1],dp[i-1][0]+a[i]);

            reverse(s[i-1].begin(),s[i-1].end());

            if(s[i]>=s[i-1])
            dp[i][1]=min(dp[i][1],dp[i-1][1]+a[i]);
            reverse(s[i-1].begin(),s[i-1].end());
            reverse(s[i].begin(),s[i].end());
        }
        if(dp[n][0]==4557430888798830399&&dp[n][1]==4557430888798830399)
        printf("-1\n");
        else
        printf("%lld\n",min(dp[n][0],dp[n][1]));
    }
    return 0;
}