Submission #1081366

#	Time	Username	Problem	Language	Result	Execution time	Memory
1081366		kes0716	Archery (IOI09_archery)	C++17	90 / 100	255 ms	10144 KiB

archery

#include <bits/stdc++.h>
using namespace std;
const int MAXN = 200009;
int n, r, crit;
int a[2*MAXN];
struct State{
	int pl, ze, mi;
	State operator+(const State &s) const{
		return (State){pl+s.pl, ze+s.ze, mi+s.mi};
	}
} init[MAXN];
int simulate1(void){
	vector<State> pot(3*n);
	State pq = {0, 0, 0};
	int i, j;
	for(i=0; i<n; i++){
		pot[i] = init[i];
	}
	int cnt = 0, last = -1;
	for(i=0; i<3*n; i++){
		pq = pq + pot[i];
		//printf("i=%d pq= +%d 0%d -%d\n", i, pq.pl, pq.ze, pq.mi);
		assert(pq.pl + pq.ze + pq.mi >= 2);
		if(pq.pl < 2 && pq.ze)
			last = i;
		if(pq.pl >= 2){
			if(i < 2*n)
				pot[i+n].pl++;
			pq.pl--;
		}
		else if(pq.pl == 1){
			if(pq.ze){
				if(i < 2*n)
					pot[i+n].ze++;
				pq.ze--;
				cnt++;
			}
			else{
				if(i < 2*n)
					pot[i+n].mi++;
				pq.mi--;
			}
		}
		else{
			if(i < 2*n)
				pot[i+n].mi++;
			pq.mi--;
		}
	}
	//printf("last=%d cnt=%d\n", last, cnt);
	int ret = last - r - n*cnt;
	if(ret%n == 0)
		ret += n;
	return ret;
}
int simulate2(int pos){
	State pq = {0, 0, 0};
	int i, ans = pos;
	for(i=2*n; i>=1; i--){
		int cur = i%n;
		pq = pq + init[cur];
		//printf("i=%d pq.pl=%d ze=%d mi=%d\n", i,pq.pl, pq.ze, pq.mi);
		init[cur].pl = init[cur].mi = init[cur].ze = 0;
		if(cur){
			if(pq.mi){
				if(pq.ze)
					ans--;
				init[cur].mi = 1;
				pq.mi--;
			}
			else if(pq.ze){
				init[cur].ze = 1;
				pq.ze--;
			}
		}
		else{
			if(pq.ze)
				ans--;
		}
	}
	return ans;
}
int simulate(int p){
	int i, j=0;
	for(i=0; i<n; i++){
		init[i].pl = init[i].ze = init[i].mi = 0;
		if(p == i)
			init[i].ze++;
		else{
			if(a[j] < crit)
				init[i].pl++;
			else
				init[i].mi++;
			j++;
		}
		if(a[j] < crit)
			init[i].pl++;
		else
			init[i].mi++;
		j++;
	}
	if(crit <= n+1)
		return simulate1();
	return simulate2(p);
}
int main(){
	int i;
	scanf("%d %d", &n, &r);
	r = 2*n + r%n;
	scanf("%d", &crit);
	for(i=0; i<2*n-1; i++){
		scanf("%d", &a[i]);
	}
	if(crit==1){
		assert(0);
		printf("%d\n", n);
		return 0;
	}
	pair<int, int> ans = make_pair(n, -1);	//(result, -start)
	for(int t=-3; t<=0; t++){
		int goal = t*n, lo = 0, hi = n-1, mid;
		while(lo < hi){
			mid = (lo+hi)/2;
			if(simulate(mid) >= goal)
				hi = mid;
			else
				lo = mid+1;
		}
		int crit = simulate(lo);
		//printf("lo=%d crit=%d\n", lo, crit);
		hi = n-1;
		while(lo < hi){
			mid = (lo+hi+1)/2;
			if(simulate(mid) == crit)
				lo = mid;
			else
				hi = mid-1;
		}
		//printf("lo=%d\n", lo);
		ans = min(ans, make_pair((crit%n + n)%n, -lo-1));
	}
	printf("%d\n", -ans.second);
	return 0;
}

Compilation message (stderr)

archery.cpp: In function 'int simulate1()':
archery.cpp:15:9: warning: unused variable 'j' [-Wunused-variable]
   15 |  int i, j;
      |         ^
archery.cpp: In function 'int main()':
archery.cpp:108:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  108 |  scanf("%d %d", &n, &r);
      |  ~~~~~^~~~~~~~~~~~~~~~~
archery.cpp:110:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  110 |  scanf("%d", &crit);
      |  ~~~~~^~~~~~~~~~~~~
archery.cpp:112:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  112 |   scanf("%d", &a[i]);
      |   ~~~~~^~~~~~~~~~~~~

• Subtask 1: 4 / 6
• Subtask 2: 86 / 94