Codeforces Round #367 (Div. 2) C. Hard problem

http://codeforces.com/contest/706/problem/C

#include<iostream>#include<string>#include<algorithm>#include<cstdio>#include<cstring>using namespace std;const int maxn = 100010;int c[maxn];string s[maxn];string rs[maxn];long long dp[maxn][2];int main(){    int n;    cin >> n;    for (int i = 1; i <= n; i++)        scanf("%d", &c[i]);    for (int i = 1; i <= n; i++) {        cin >> s[i];        rs[i] = s[i];        reverse(rs[i].begin(), rs[i].end());    }    s[0] = rs[0] = "";    memset(dp, 0x3f, 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]);         if (rs[i] >= s[i - 1])            dp[i][1] = min(dp[i][1], c[i] + dp[i - 1][0]);        if (s[i] >= rs[i - 1])            dp[i][0] = min(dp[i][0], dp[i - 1][1]);        if (rs[i] >= rs[i - 1])            dp[i][1] = min(dp[i][1], c[i] + dp[i - 1][1]);          }    long long ans = min(dp[n][0], dp[n][1]);    if (ans > 1e15)        cout << "-1" << endl;    else        cout << ans << endl;    return 0;}