交互题(apio2016Gap)

题目链接

 

//Serene
#include<algorithm>
#include<iostream>
#include<cstring>
#include<cstdlib>
#include<cstdio>
#include<cmath>
#include "gap.h"
using namespace std;
#define ll long long
#define db double
#define For(i,a,b) for(int i=(a);i<=(b);++i)
#define Rep(i,a,b) for(int i=(a);i>=(b);--i)

ll findGap(int T,int N) {
	ll n=(N+1)>>1,l=0,r=1e18,ld,rd,rs=0,fl=0,len;
	if(T==1) {
		MinMax(l,r,&ld,&rd); l=ld; r=rd;
		For(i,1,n-1) {
			MinMax(l+1,r-1,&ld,&rd);
			rs=max(rs,ld-l); rs=max(rs,r-rd);
			l=ld; r=rd;
			if((r-1)-(l+1)<=rs) {fl=1; break;}
		}
		if(!fl) rs=max(rs,rd-ld);
		return rs;
	}
	else {
		MinMax(l,r,&ld,&rd); l=ld; r=rd; len=(r-l+N-2)/(N-1);
		ll lst=l;
		for(ll now=l;now<r-1;now+=len) {
			MinMax(now+1,min(now+len,r-1),&ld,&rd);
			if(~ld) rs=max(rs,ld-lst),lst=rd;
		}
		rs=max(rs,r-lst);
		return rs;
	}
}

编译：

g++ -g gap.cpp grader.cpp -o gap

grader.cpp

#include <stdio.h>
#include <stdlib.h>

#include "gap.h"

static void my_assert(int k){ if (!k) exit(1); }

static int subtask_num, N;
static long long A[100001];
static long long call_count;

long long findGap(int, int);

void MinMax(long long s, long long t, long long *mn, long long *mx)
{
	int lo = 1, hi = N, left = N+1, right = 0;
	my_assert(s <= t && mn != NULL && mx != NULL);
	while (lo <= hi){
		int mid = (lo+hi)>>1;
		if (A[mid] >= s) hi = mid - 1, left = mid;
		else lo = mid + 1;
	}
	lo = 1, hi = N;
	while (lo <= hi){
		int mid = (lo+hi)>>1;
		if (A[mid] <= t) lo = mid + 1, right = mid;
		else hi = mid - 1;
	}
	if (left > right) *mn = *mx = -1;
	else{
		*mn = A[left];
		*mx = A[right];
	}
	if (subtask_num == 1) call_count++;
	else if (subtask_num == 2) call_count += right-left+2;
}

int main()
{
//	freopen("gap.in","r",stdin);
//	freopen("gap.out","w",stdout);
	FILE *in = stdin, *out = stdout;
	my_assert(2 == fscanf(in, "%d%d", &subtask_num, &N));
	my_assert(1 <= subtask_num && subtask_num <= 2);
	my_assert(2 <= N && N <= 100000);
	for (int i=1;i<=N;i++) my_assert(1 == fscanf(in, "%lld", A+i));
	for (int i=1;i<N;i++) my_assert(A[i] < A[i+1]);
	fprintf(out, "%lld\n", findGap(subtask_num, N));
	fprintf(out, "%lld\n", call_count);
}

gap.h

void MinMax(long long, long long, long long*, long long*);