HDU 2577 How to Type(dp)

题目链接：HDU 2577 How to Type

dp。

notlock[i]表示type第i个字母后大写锁定键为关闭状态的最少type次数，lock[i]表示type第i个字母后大写锁定键为开启状态的最少type次数。

状态转移方程：

s[i]为大写字母：

lock[i] = min(lock[i - 1] + 1,notlock[i - 1] + 2);
notlock[i] = min(notlock[i - 1] + 2,lock[i - 1] + 2);

s[i]为小写字母：

lock[i] = min(lock[i - 1] + 2,notlock[i - 1] + 2);
notlock[i] = min(lock[i - 1] + 2,notlock[i - 1] + 1);

最后输出时候需要判断一下notlock[len - 1] 和 lock[len - 1] + 1的大小。

#include <iostream>
#include <cstring>

using namespace std;
const int MAX_N = 100 + 10;
int notlock[MAX_N],lock[MAX_N];
int t;
char s[MAX_N];

int main()
{
    cin >> t;
    while(t--)
    {
        memset(notlock,0,sizeof(notlock));
        memset(lock,0,sizeof(lock));
        cin >> s;
        int len = strlen(s);
        if(s[0] >= 'A' && s[0] <= 'Z')
            lock[0] = notlock[0] = 2;
        else
        {
            lock[0] = 2;
            notlock[0] = 1;
        }
        for(int i = 1;i < len;i++)
        {
            if(s[i] >= 'A' && s[i] <= 'Z')
            {
                lock[i] = min(lock[i - 1] + 1,notlock[i - 1] + 2);
                notlock[i] = min(notlock[i - 1] + 2,lock[i - 1] + 2);
            }
            else
            {
                lock[i] = min(lock[i - 1] + 2,notlock[i - 1] + 2);
                notlock[i] = min(lock[i - 1] + 2,notlock[i - 1] + 1);
            }
        }
        cout << (notlock[len - 1] < lock[len - 1] + 1 ? notlock[len - 1] : lock[len - 1] + 1) << endl;
    }
    return 0;
}