Codeforces 508C

CodeForces 508C

题意：有m个鬼会来拜访你，每个鬼拜访你的时间wi给出，每次拜访都是1s，你有一些蜡烛，你要保证每次鬼拜访你的时候都有最少r根蜡烛亮着才不会害怕，每根蜡烛燃烧的时间是t，点燃一根蜡烛花费1s时间，也就是在x时间点蜡烛，x+1到x+1+t是亮的，现在求最少花费多少蜡烛，如果不能使每个鬼拜访你的时候都有r个蜡烛亮着输出-1

思路：树状数组+扫描线，每次判断当前时间是否有r个蜡烛亮着，如果不够就往前加，尽量在靠后的时间点蜡烛，有一点注意，最多同时使t个蜡烛保持亮的状态

AC代码：

#include "iostream"
#include "string.h"
#include "stack"
#include "queue"
#include "string"
#include "vector"
#include "set"
#include "map"
#include "algorithm"
#include "stdio.h"
#include "math.h"
#pragma comment(linker, "/STACK:102400000,102400000")
#define ll long long
#define endl ("\n")
#define bug(x) cout<<x<<" "<<"UUUUU"<<endl;
#define mem(a,x) memset(a,x,sizeof(a))
#define mp(x,y) make_pair(x,y)
#define pb(x) push_back(x)
#define ft (frist)
#define sd (second)
#define lrt (rt<<1)
#define rrt (rt<<1|1)
using namespace std;
const long long INF = 1e18+1LL;
const int inf = 1e9+1e8;
const double eps=1e-4;
const int N=6e4+100;
const ll mod=1e9+7;

int m,t,r,ans,w[305];
int C[615];
int lowbit(int x){
    return (-x)&x;
}
int sum(int x){
    int ret=0;
    while(x>0){
        ret+=C[x];
        x-=lowbit(x);
    }
    return ret;
}
void add(int x, int z){
    while(x<=610){
        C[x]+=z;
        x+=lowbit(x);
    }
}

int main(){
    ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
    cin>>m>>t>>r;
    if(r>t){
        cout<<-1;
        return 0;
    }
    for(int i=1; i<=m; ++i){
        cin>>w[i];//cout<<sum(w[i]+300)<<endl;
        if(sum(w[i]+305)<r){
            int c=r-sum(w[i]+305); ans+=c;
            for(int ti=w[i]-c; ti<w[i]; ++ti){ //cout<<ti+300+1<<" "<<ti+t+1+300<<endl;
                add(ti+305,1), add(ti+t+1+305,-1);
            }
        }
    }
    cout<<ans<<endl;
    return 0;
}