A. Vacations：题目

题意：每天有四种可能性，锻炼和比赛分别两种可能性相乘。不能连续锻炼或者连续比赛，问最少休息几天。
思路：dp或者贪心都行。

贪心写法

#include <bits/stdc++.h>
using namespace std;
vector<int> a(111);
int main()
{int n;cin >> n;for (int i = 1; i <= n; i++){cin >> a[i];}int res = 0;for (int i=1;i<=n;i++){if (a[i]==0) res++;else if (a[i]==1){if (a[i-1]==1) res++,a[i] = 0;}else if (a[i]==2) {if (a[i-1]==2) res++,a[i] = 0;}else if (a[i]==3){if (a[i-1]==1) {a[i] = 2;}else if (a[i-1]==2){a[i] = 1;}}}cout<<res<<endl;return 0;
}

动态规划写法

#include <bits/stdc++.h>
using namespace std;
vector<int> a(111)
int main()
{int n;cin >> n;for (int i = 0; i < n; i++){cin >> a[i];}vector<int> ve(3);ve[0] = ve[1] = ve[2] = 0;for (int i = 0; i < n; i++){vector<int> nve(3);nve[1] = nve[2] = 101;//取最大值，防止为0.nve[0] = min(ve[0], min(ve[1], ve[2])) + 1;if (a[i] == 1 || a[i] == 3){nve[1] = min(ve[0], ve[2]);}if (a[i] == 2 || a[i] == 3){nve[2] = min(ve[0], ve[1]);}swap(nve,ve);}int res = min(ve[0],min(ve[1],ve[2]));cout << res << endl;return 0;
}