HDU 2577 How to Type(DP)

来源：互联网发布：电子设备审计软件功能编辑：程序博客网时间：2024/05/21 09:38

题意：编辑一个字符串，初始时caps lock为关闭状态，问至少敲击多少次按键可以敲出给出的字符串，且最后时caps lock为关闭状态。也可以用Shift输入大写字母，Shift也算一次敲击。

分析：典型的dp。dp[i][0]表示敲完第i个字符时的最少敲击次数且此时caps lock为关闭的状态，dp[i][1]表示为打开的状态。那么当第i个字符为大写字母时，有转移方程：dp[i][1] = min(dp[i-1][1] + 1, dp[i-1][0] + 2); dp[i][0] = min(dp[i-1][1] + 2, dp[i-1][0] + 2);为小写字母时，转移方程：dp[i][0] = min(dp[i-1][0] + 1, dp[i-1][1] + 2); dp[i][1] = dp[i-1][1] + 2；

代码：

#include <algorithm>#include <iostream>#include <sstream>#include <cstring>#include <cstdio>#include <vector>#include <string>#include <queue>#include <stack>#include <cmath>#include <set>#include <map>using namespace std;typedef long long LL;#define mem(a, n) memset(a, n, sizeof(a))#define ALL(v) v.begin(), v.end()#define si(a) scanf("%d", &a)#define sii(a, b) scanf("%d%d", &a, &b)#define siii(a, b, c) scanf("%d%d%d", &a, &b, &c)#define pb push_back#define eps 1e-8const int inf = 0x3f3f3f3f, N = 1e2 + 5, MOD = 1e9 + 7;int T, cas = 0;int n, m;int dp[N][2];char s[N];int main(){#ifdef LOCAL    freopen("/Users/apple/input.txt", "r", stdin);//freopen("/Users/apple/out.txt", "w", stdout);#endif    si(T);    while(T --) {    scanf("%s", s + 1);    n = strlen(s + 1);    mem(dp, 0);    dp[0][1] = 1;    for(int i = 1; i <= n; i ++) {    if(s[i] >= 'A' && s[i] <= 'Z') {dp[i][1] = min(dp[i-1][1] + 1, dp[i-1][0] + 2);dp[i][0] = min(dp[i-1][1] + 2, dp[i-1][0] + 2);} else {dp[i][0] = min(dp[i-1][0] + 1, dp[i-1][1] + 2);dp[i][1] = dp[i-1][1] + 2;}    }    printf("%d\n", dp[n][0]);    }        return 0;}

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