51Nod 1521 一维战舰

http://www.51nod.com/onlineJudge/questionCode.html#!problemId=1521

思路：
先计算出一开始最多能放多少艘战舰，然后每次输入一个点后，找到所在区间，计算出插入这个点后减少的可放战舰数量。

#include<iostream>
#include<algorithm>
#include<cstring>
#include<cstdio>
#include<vector>
#include<stack>
#include<queue>
#include<cmath>
using namespace std;

const int maxn=2*1e5+5;

int n,k,a;
int c[maxn];

int main()
{
    //freopen("D:\input.txt","r",stdin);
    while(~scanf("%d%d%d",&n,&k,&a))
    {
        memset(c,0,sizeof(c));
        int max_k=(n+1)/(a+1);
        int m;
        scanf("%d",&m);
        int ans=-1;
        for(int i=1;i<=m;i++)
        {
            int x;
            scanf("%d",&x);
            if(ans!=-1)  continue;
            c[x]=1;
            int left=x-1,right=x+1;
            while(left>=1 && c[left]==0)      left--;
            while(right<=n && c[right]==0)    right++;
            max_k-=((right-left)/(a+1)-(right-x)/(a+1)-(x-left)/(a+1));
            if(ans==-1 && max_k<k)
                ans=i;
        }
        printf("%d
",ans);
    }
    return 0;
}