HDU 2577 How to Type(dp)

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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;}

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