D - 船之戰
Alice and Bob love playing one-dimensional battle ships. They play on the field in the form of a line consisting of n square cells (that is, on a 1?×?n table).
At the beginning of the game Alice puts k ships on the field without telling their positions to Bob. Each ship looks as a 1?×?a rectangle (that is, it occupies a sequence of a
After that Bob makes a sequence of "shots". He names cells of the field and Alice either says that the cell is empty ("miss"), or that the cell belongs to some ship ("hit").
But here‘s the problem! Alice like to cheat. May be that is why she responds to each Bob‘s move with a "miss".
Help Bob catch Alice cheating — find Bob‘s first move, such that after it you can be sure that Alice cheated.
Input
The first line of the input contains three integers: n, k and a (1?≤?n,?k,?a?≤?2·105) — the size of the field, the number of the ships and the size of each ship. It is guaranteed that the n
The second line contains integer m (1?≤?m?≤?n) — the number of Bob‘s moves.
The third line contains m distinct integers x1,?x2,?...,?xm, where xi is the number of the cell where Bob made the i-th shot. The cells are numbered from left to right from 1 to n.
Output
Print a single integer — the number of such Bob‘s first move, after which you can be sure that Alice lied. Bob‘s moves are numbered from 1 to m in the order the were made. If the sought move doesn‘t exist, then print "-1".
Example
Input11 3 3Output
5
4 8 6 1 11
3
Input
5 1 3Output
2
1 5
-1
Input
5 1 3Output
1
3
1
解法:
1 #include <iostream>
2 #include <string.h>
3 #include <set>
4 #include <stack>
5 using namespace std;
6
7 const int MAX = 5*100000 + 2000;
8
9 int main()
10 {
11 int ti =-1;
12 set<int>s;
13 int L,n,l;
14 int N;
15 cin>>L>>n>>l>>N;
16 s.insert(0);
17 s.insert(L+1);
18 int sum = (L+1)/(l+1);
19 for(int i = 0;i < N;i++)
20 {
21 int temp;
22 cin>>temp;
23 set<int>::iterator it;
24 if(!s.empty())
25 {
26 int temp1,temp2;
27 it = s.lower_bound(temp);
28 temp1 = *it ;
29 temp2 = *(--it);
30 sum = sum - (temp1 -temp2)/(l+1) + (temp - temp2)/(l+1) +(temp1 - temp)/(l+1);
31 // cout<<"temp1 == temp2 =sum == "<<temp1<<temp2<<sum<<endl;
32 }
33 s.insert(temp);
34
35 if(sum < n)
36 {
37 ti = i+1;
38 break;
39 }
40 }
41
42 cout<<ti<<endl;
43
44 return 0;
45 }
D - 船之戰