LuoguP1725 琪露诺 (动态规划)

\(单调队列\) 或 \(堆\) 优化

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#define R(a,b,c) for(register int  a = (b); a <= (c); ++ a)
#define nR(a,b,c) for(register int  a = (b); a >= (c); -- a)
#define Max(a,b) ((a) > (b) ? (a) : (b))
#define Min(a,b) ((a) < (b) ? (a) : (b))
#define Fill(a,b) memset(a, b, sizeof(a))
#define Swap(a,b) a^=b^=a^=b
#define ll long long
#define ON_DEBUG

#ifdef ON_DEBUG

#define D_e_Line printf("\n\n----------\n\n")
#define D_e(x)  cout << #x << " = " << x << endl
#define Pause() system("pause")

#else

#define D_e_Line ;

#endif

struct ios{
    template<typename ATP>ios& operator >> (ATP &x){
        x = 0; int f = 1; char c;
        for(c = getchar(); c < '0' || c > '9'; c = getchar()) if(c == '-')  f = -1;
        while(c >= '0' && c <= '9') x = x * 10 + (c ^ '0'), c = getchar();
        x*= f;
        return *this;
    }
}io;
using namespace std;

const int N = 200007;

int l, r;
int f[N];
int a[N];
int q[N];
int id[N];

int h = 1, t = 1;
inline int Position(int x){
	while(q[t] <= f[x] && t >= h) --t;
	q[++t] = f[x];
	id[t] = x;
	while(q[h] + r < x) ++h;
	return id[h];
}
int main(){
    int n;
    io >> n >> l >> r;
    R(i,0,n){
    	io >> a[i];
    	f[i] = 0xcfcfcfcf;
    }
    f[0] = 0;
    int ans = 0xcfcfcfcf;
    R(i,l,n){
        int j = Position(i - l);
        f[i] = f[j] + a[i];
        if(i >= n - r + 1)
          ans = Max(ans, f[i]);
    }
    
    printf("%d",ans);
    
    return 0;
}