CF1291

A

 1 #include <cstdio>
 2 using namespace std;
 3 int T,n,sum,num[3100];
 4 char str[3100];
 5 bool suc;
 6 int main()
 7 {
 8     for (scanf("%d",&T);T;T--)
 9     {
10         suc = false;
11         sum = 0;
12         scanf("%d%s",&n,str + 1);
13         for (int i = 1;i <= n;i++)
14         {
15             num[i] = str[i] - '0';
16             sum += num[i];
17         }
18         int i; 
19         for (i = n;i >= 1;i--)
20             if ((num[i] & 1) == 0)
21             {
22                 sum -= num[i];
23                 num[i] = -1;
24             }else
25             {
26                 suc = true;
27                 break;
28             }
29         if (suc == false)
30         {
31             printf("-1\n");
32             continue;
33         }
34         if ((sum & 1) != 0)
35             for (i--;i >= 1;i--)
36                 if (num[i] != -1 && (num[i] & 1))
37                 {
38                     sum -= num[i];
39                     num[i] = -1;
40                     break;
41                 }
42         if ((sum & 1) != 0 || sum == 0)
43         {
44             printf("-1\n");
45             continue;
46         }
47         for (int i = 1;i <= n;i++)
48             if (num[i] == 0)
49                 num[i] = -1;
50             else
51                 break;
52         for (int i = 1;i <= n;i++)
53             if (num[i] != -1)
54                 printf("%d",num[i]);
55         printf("\n");
56     }
57     return 0;
58 }

B

 1 #include <cstdio>
 2 using namespace std;
 3 int T,n,left,right;
 4 int a[310000];
 5 int main()
 6 {
 7     for (scanf("%d",&T);T;T--)
 8     {
 9         scanf("%d",&n);
10         left = 0;
11         right = n - 1;
12         for (int i = 1;i <= n;i++)
13             scanf("%d",&a[i]);
14         for (int i = 1;i <= n;i++)
15             if (a[i] < i - 1)
16                 break;
17             else
18                 left = i;
19         for (int i = n;i >= 1;i--)
20             if (a[i] < n - i)
21                 break;
22             else
23                 right = i;
24         if (left >= right)
25             printf("Yes\n");
26         else
27             printf("No\n");
28     }
29     
30     return 0;
31 }

C

 1 #include <cstdio>
 2 #include <algorithm>
 3 using namespace std;
 4 int T,n,m,k,a[4100],ans,tres;
 5 int main()
 6 {
 7     for (scanf("%d",&T);T;T--)
 8     {
 9         ans = 0;
10         scanf("%d%d%d",&n,&m,&k);
11         for (int i = 1;i <= n;i++)
12             scanf("%d",&a[i]);
13         k = min(k,m - 1);
14         for (int i = 0;i <= k;i++)
15         {
16             //l:1 + i r:n - (k - i)
17             tres = 2000000000;
18             for (int j = 0;j <= m - k - 1;j++)
19             //l:1 + i + j  r: 
20                 tres = min(tres,max(a[1 + i + j],a[n  + i - m + j + 1]));
21             ans = max(ans,tres);
22         }
23         printf("%d\n",ans);
24     }
25 }

D

 1 #include <cstdio>
 2 #include <cmath>
 3 #include <cstring>
 4 #include <algorithm>
 5 using namespace std;
 6 struct dat
 7 {
 8     int l,r,id;
 9     bool res;
10 } qry[110000];
11 char s[210000];
12 int q,B,sum,cnt[200];
13 bool cmp1(dat a,dat b)
14 {
15     if (a.l / B != b.l / B)
16         return a.l < b.l;
17     return a.r < b.r;
18 }
19 bool cmp2(dat a,dat b)
20 {
21     return a.id < b.id;
22 }
23 void add(int x)
24 {
25     if (cnt[s[x]] == 0)
26         sum++;
27     cnt[s[x]]++;
28 }
29 void des(int x)
30 {
31     if (cnt[s[x]] == 1)
32         sum--;
33     cnt[s[x]]--;
34 }
35 int main()
36 {
37     scanf("%s%d",s + 1,&q);
38     B = sqrt(strlen(s + 1)); 
39     for (int i = 1;i <= q;i++)
40     {
41         scanf("%d%d",&qry[i].l,&qry[i].r);
42         qry[i].id = i;
43     }
44     sort(qry + 1,qry + q + 1,cmp1);
45     int l = qry[1].l,r = qry[1].r;
46     for (int i = l;i <= r;i++)
47         add(i);
48     if (qry[1].l == qry[1].r || s[qry[1].l] != s[qry[1].r] || sum >= 3)
49             qry[1].res = true;
50     for (int i = 2;i <= q;i++)
51     {
52         
53         if (qry[i].l == qry[i].r || s[qry[i].l] != s[qry[i].r])
54         {
55             qry[i].res = true;
56             continue;
57         }
58         while (l < qry[i].l)
59             des(l++);
60         while (l > qry[i].l)
61             add(--l);
62         while (r < qry[i].r)
63             add(++r);
64         while (r > qry[i].r)
65             des(r--);
66         if (sum >= 3)
67             qry[i].res = true;
68     }
69     sort(qry + 1,qry + q + 1,cmp2);
70     for (int i = 1;i <= q;i++)
71         printf("%s\n",qry[i].res ? "Yes" : "No");
72     return 0;
73 }

E

 1 #include <cstdio>
 2 #include <algorithm>
 3 using namespace std;
 4 const int MAXN = 810000;
 5 int fa[MAXN],val[MAXN],vec[MAXN][3];
 6 int n,k,ans;
 7 char str[MAXN];
 8 int getfa(int x)
 9 {
10     if (fa[x] == x)
11         return x;
12     return fa[x] = getfa(fa[x]);
13 }
14 void merge(int x,int y)
15 {
16     int p = getfa(x),q = getfa(y);
17     if (p == q)
18         return;
19     fa[p] = q;
20     val[q] += val[p]; 
21 }
22 int getval(int x)
23 {
24     return min(val[getfa(x)],val[getfa(x + k)]);
25 }
26 int main()
27 {
28     scanf("%d%d%s",&n,&k,str + 1);
29     int tc;
30     for (int i = 1;i <= k;i++)
31     {
32         scanf("%d",&tc);
33         int tx;
34         for (int j = 1;j <= tc;j++)
35         {
36             scanf("%d",&tx);
37             vec[tx][++vec[tx][0]] = i;
38         }
39     }
40     for (int i = 1;i <= k;i++)
41         fa[i] = i,val[i] = 0;
42     for (int i = k + 1;i <= 2 * k;i++)
43         fa[i] = i,val[i] = 1;
44     fa[k << 1 | 1] = k << 1 | 1;
45     val[k << 1 | 1] = 1000000;
46     for (int i = 1;i <= n;i++)
47     {
48         if (vec[i][0] == 2)
49         {
50             if (str[i] == '0')
51             {
52                 if (getfa(vec[i][1]) != getfa(vec[i][2] + k))
53                 { 
54                     ans -= getval(vec[i][1]) + getval(vec[i][2]);
55                     merge(vec[i][1],vec[i][2] + k);
56                     merge(vec[i][1] + k,vec[i][2]);
57                     ans += getval(vec[i][1]);
58                 }
59             }else
60             {
61                 if (getfa(vec[i][1]) != getfa(vec[i][2]))
62                 {
63                     ans -= getval(vec[i][1]) + getval(vec[i][2]);
64                     merge(vec[i][1] + k,vec[i][2] + k);
65                     merge(vec[i][1],vec[i][2]);
66                     ans += getval(vec[i][1]);
67                 }
68             }
69         }else if (vec[i][0] == 1)
70         {
71             if (str[i] == '0')
72             {
73                 ans -= getval(vec[i][1]);
74                 merge(vec[i][1],k << 1 | 1);
75                 ans += getval(vec[i][1]);
76             }else
77             {
78                 ans -= getval(vec[i][1]);
79                 merge(vec[i][1] + k,k << 1 | 1);
80                 ans += getval(vec[i][1]);
81             }
82         }
83         printf("%d\n",ans);
84     }
85     return 0;
86 }

 

posted @ 2020-02-05 14:33  IAT14  阅读(181)  评论(0)  编辑  收藏  举报