제출 #538599

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
538599		chaoyue	선물상자 (IOI15_boxes)	C++14	0 / 100	1 ms	468 KiB

boxes

#include <bits/stdc++.h>
#include "boxes.h"
using namespace std;

#define ll long long

ll delivery(int N, int K, int L, int p[]){
	ll split = L/2, idx=0, lsize=1, rsize=1, f0, ans;
	vector<ll> left(N), right(N);
	left[0] = 0, right[0] = 0;
	while(idx < N && p[idx] <= split){
		left[lsize] = p[idx] * 2;
		if(lsize >= K) left[lsize] += left[lsize-K];
		idx++, lsize++;
	}
	while(idx < N){
		right[rsize] = (L - p[idx]) * 2;
		if(rsize >= K) right[rsize] += right[rsize-K];
		idx++, rsize++;
	}
	//left is non-decreasing
	//pre array will flip left & right arrays
	vector<ll> lpre(lsize), rpre(rsize);
	lpre[0] = 0; rpre[0] = 0;
	for(ll i=1; i<lsize; i++){
		lpre[i] = lpre[i-1] + left[lsize-i] - left[lsize-i-1];
	}
	for(ll i=1; i<rsize; i++){
		rpre[i] = rpre[i-1] + right[rsize-i] - right[rsize-i-i];
	}
	f0 = left[lsize-1] + right[rsize-1];  //initial answer if 0 loops
	vector<ll> opt(K, 0);  //calculates optimal value of lpre assuming rpre takes i souvenirs
	for(ll i=0; i<K; i++){
		for(ll j=0; j<N/K; j++){
			idx = K - i + j*K;
			opt[idx] = max(opt[idx], lpre[idx] - (j+1) * N);
		}
	}
	for(int i=0; i<rsize; i++){
		ans = max(ans, rpre[i] + opt[i%K] - i/K);
	}
	ans = max(f0, f0-ans);
    return ans;
}

컴파일 시 표준 에러 (stderr) 메시지

boxes.cpp: In function 'long long int delivery(int, int, int, int*)':
boxes.cpp:8:47: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
    8 |  ll split = L/2, idx=0, lsize=1, rsize=1, f0, ans;
      |                                               ^~~

• Subtask 1: 0 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 15
• Subtask 4: 0 / 15
• Subtask 5: 0 / 20
• Subtask 6: 0 / 30