Submission #470098

#	Time	Username	Problem	Language	Result	Execution time	Memory
470098		dantoh000	Cat (info1cup19_cat)	C++14	21.25 / 100	369 ms	1840 KiB

cat

#include <bits/stdc++.h>
using namespace std;
int main(){
    int t;
    scanf("%d",&t);
    while (t--){
        int n;
        scanf("%d",&n);
        vector<int> a(n+1,0);
        vector<int> vis(n/2+1,0);
        vector<int> marked(n/2+1,0);
        for (int i = 1; i <= n; i++){
            scanf("%d",&a[i]);
        }
        bool can = true;
        int sw = 0;
        int extra = 0;
        int hmm = 0;
        for (int i = 1; i <= n/2; i++){
            if (a[i]+a[n+1-i] != n+1) can = false;
            if (a[i] > n/2){
                sw++;
                marked[i] = 1;
                a[i] = n+1-a[i];
                if (a[i] == i) hmm++;
            }
        }
        if (sw % 2 != 0) can = false;
        if (!can){
            printf("-1\n");
            continue;
        }
        int ans = 0;
        for (int i = 1; i <= n/2; i++){
            //printf("%d ",a[i]);
            if (vis[i] == 0){

                int ct = 0;
                vis[i] = 1;
                ct += marked[i];
                int len = 1;
                int cur = a[i];
                while (cur != i){
                    ct += marked[cur];
                    len++;
                    vis[cur] = 1;
                    cur = a[cur];
                }
                //printf("ct = %d len = %d\n",ct,len);
                if (ct % 2 == 0){
                    ans += len-1;
                }
                else{
                    if (len == 1 && ct == 1) continue;
                    ans += len;
                    extra ++;
                }

            }
        }
        ans -= extra/2;
        ans += hmm/2;
        if (hmm % 2 == 1) ans++;

        printf("%d 0\n",ans);


    }


}

Compilation message (stderr)

cat.cpp: In function 'int main()':
cat.cpp:5:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
    5 |     scanf("%d",&t);
      |     ~~~~~^~~~~~~~~
cat.cpp:8:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
    8 |         scanf("%d",&n);
      |         ~~~~~^~~~~~~~~
cat.cpp:13:18: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   13 |             scanf("%d",&a[i]);
      |             ~~~~~^~~~~~~~~~~~

• Subtask 1: 2.25 / 15
• Subtask 2: 4 / 10
• Subtask 3: 3.75 / 25
• Subtask 4: 6 / 15
• Subtask 5: 5.25 / 35