pat乙级每日习题

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1：https://pintia.cn/problem-sets/994805260223102976/problems/994805325918486528

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3
 4 int main(int argc, char const *argv[])
 5 {
 6     int n;cin >> n;
 7     int ans = 0;
 8     while(n != 1){
 9         if((n & 1) == 1){
10             n = (n * 3 + 1) >> 1;
11         }else{
12             n >>= 1;
13         }
14         ++ans;
15     }
16     cout << ans << endl;
17     return 0;
18 }

2：https://pintia.cn/problem-sets/994805260223102976/problems/994805320306507776

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3
 4 const int N = 110;
 5
 6 int arr[N];
 7 int n;
 8
 9 int main(int argc, char const *argv[])
10 {
11     unordered_map<int, bool> hash;
12
13     cin >> n;
14     for(int i = 1;i <= n;++i){
15         cin >> arr[i];//存进数组因为求答案要用
16         int x = arr[i];
17         //把x最终变成1的所有中间的数都置为true，代表出现过
18         while(x != 1){
19             if((x & 1) == 1) //&1 == 1 代表是奇数
20                 x = (3 * x + 1) >> 1;
21             else
22                 x >>= 1;
23             hash[x] = true;
24         }
25     }
26
27     vector<int> ans;
28     //把数组中的数没有被覆盖过的也就是 false 的加进答案
29     for(int i = 1;i <= n;++i)
30         if(!hash[arr[i]])
31             ans.push_back(arr[i]);
32     //以下代码完全是为了格式化输出
33     sort(ans.begin(), ans.end(), greater<int>());
34     for(int i = 0;i < ans.size()-1;++i)
35         cout << ans[i] << " ";
36     cout << ans[ans.size()-1];
37     cout << endl;
38
39     return 0;
40 }

3：https://pintia.cn/problem-sets/994805260223102976/problems/994805317546655744

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3
 4 const int N = 1e5;
 5
 6 int n;
 7 bool state[N];
 8
 9 int main(int argc, char const *argv[])
10 {
11     cin >> n;
12     int ans = 0;
13     int pre = -1;
14     for(int i = 2;i <= n;++i){
15         if(!state[i]){
16             if(i - pre == 2)
17                 ++ans;
18             pre = i;
19             for(int j = i + i; j <= n; j += i)
20                 state[j] = true;
21         }
22     }
23     cout << ans << endl;
24     return 0;
25 }

4:https://pintia.cn/problem-sets/994805260223102976/problems/994805296180871168

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3
 4 const int N = 1e5+10;
 5
 6 struct Node{
 7     int val;
 8     int next;
 9 }node[N];
10
11 int head;
12 int n, k;
13
14 int revers(int cur, int t){
15     int pre = -1;
16     while(cur != t){
17         int tmp = node[cur].next;
18         node[cur].next = pre;
19         pre = cur;
20         cur = tmp;
21     }
22     return pre;
23 }
24
25 int help(int h){
26     if(h == -1) return h;
27     int tail = h;
28     for(int i = 0;i < k;++i){
29         tail = node[tail].next;
30         if(tail == -1) return h;
31     }
32     int newh = revers(h, tail);
33     node[h].next = help(tail);
34     return newh;
35 }
36
37 int main(){
38     cin >> head >> n >> k;
39     for(int i = 1;i <= n;++i){
40         int x;cin >> x;
41         cin >> node[x].val >> node[x].next;
42     }
43     int newhead = help(head);
44     for(int i = newhead;i != -1;i = node[i].next)
45         if(node[i].next == -1)
46             printf("%05d %d %d\n", i, node[i].val, node[i].next);
47         else
48             printf("%05d %d %05d\n", i, node[i].val, node[i].next);
49     return 0;
50 }

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