codeforces round367 div2.C (DP)

题目链接：http://codeforces.com/contest/706/problem/C

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N=1e5+3;
const ll INF=1e18;
ll dp[N][2];
string a[N],b[N];
int c[N];
int main()
{
    int n;
    scanf("%d",&n);
    for(int i=0;i<n;i++)
        scanf("%d",c+i);
    for(int i=0;i<n;i++)
    {
        cin>>a[i];
        b[i]=a[i];
        reverse(b[i].begin(),b[i].end());
    }
    for(int i=1;i<n;i++)
        dp[i][0]=dp[i][1]=INF;
    dp[0][1]=c[0];
    int i;
    for(i=1;i<n;i++)
    {
        if(a[i]>=a[i-1])
            dp[i][0]=dp[i-1][0];
        if(b[i]>=a[i-1])
            dp[i][1]=dp[i-1][0]+c[i];
        if(a[i]>=b[i-1])
            dp[i][0]=min(dp[i][0],dp[i-1][1]);
        if(b[i]>=b[i-1])
            dp[i][1]=min(dp[i][1],dp[i-1][1]+c[i]);
        if(dp[i][0]==INF&&dp[i][1]==INF)
            break;
    }
    if(i==n)
        printf("%I64d\n",min(dp[n-1][0],dp[n-1][1]));
    else
        printf("-1\n");
    return 0;
}