Codeforces Round #412 (rated, Div. 2, base on VK Cup 2017 Round 3) E. Prairie Partition 二分+贪心
It can be shown that any positive integer x can be uniquely represented as x = 1 + 2 + 4 + ... + 2k - 1 + r, where k and r are integers, k ≥ 0, 0 < r ≤ 2k. Let's call that representation prairie partition of x.
For example, the prairie partitions of 12, 17, 7 and 1 are:
12 = 1 + 2 + 4 + 5,
17 = 1 + 2 + 4 + 8 + 2,
7 = 1 + 2 + 4,
1 = 1.
Alice took a sequence of positive integers (possibly with repeating elements), replaced every element with the sequence of summands in its prairie partition, arranged the resulting numbers in non-decreasing order and gave them to Borys. Now Borys wonders how many elements Alice's original sequence could contain. Find all possible options!
The first line contains a single integer n (1 ≤ n ≤ 105) — the number of numbers given from Alice to Borys.
The second line contains n integers a1, a2, ..., an (1 ≤ ai ≤ 1012; a1 ≤ a2 ≤ ... ≤ an) — the numbers given from Alice to Borys.
Output, in increasing order, all possible values of m such that there exists a sequence of positive integers of length m such that if you replace every element with the summands in its prairie partition and arrange the resulting numbers in non-decreasing order, you will get the sequence given in the input.
If there are no such values of m, output a single integer -1.
- 8
1 1 2 2 3 4 5 8
- 2
In the first example, Alice could get the input sequence from [6, 20] as the original sequence.
In the second example, Alice's original sequence could be either [4, 5] or [3, 3, 3].
题意:
每个数都可以表示成2的连续次方和加上一个r
例如:12 = 1 + 2 + 4 + 5,
17 = 1 + 2 + 4 + 8 + 2,
现在给你这些数,让你反过来组成12,17,但是是有不同方案的
看看样列就懂了,问你方案的长度种类
题解:
将所有连续的2^x,处理出来,假设有now个序列
最后剩下的数,我们必须将其放到上面now的尾端,但是我们优先放与当前值最接近的序列尾端,以防大一些的数仍然有位置可以放
处理出满足条件最多序列数
二分最少的能满足条件的序列数,也就是将mid个序列全部插入到上面now-mid个序列尾端,这里贪心选择2^x,x小的
- #include<bits/stdc++.h>
- using namespace std;
- #pragma comment(linker, "/STACK:102400000,102400000")
- #define ls i<<1
- #define rs ls | 1
- #define mid ((ll+rr)>>1)
- #define pii pair<int,int>
- #define MP make_pair
- typedef long long LL;
- const long long INF = 1e18+1LL;
- const double Pi = acos(-1.0);
- const int N = 1e5+, M = 1e3+, mod = 1e9+,inf = 2e9;
- LL H[],a[N];
- int No,cnt[N],n,cnts;
- vector<LL > G,ans;
- vector<LL > all[N];
- int sum[N],sum2[N];
- pair<int,LL> P[N];
- void go(LL x) {
- int i;
- for(i = ; i <= ; ++i) {
- if(x < H[i])
- break;
- }
- i--;
- for(int j = ; j <= i; ++j) {
- cnt[j]--;
- if(cnt[j] < ) No = ;
- return ;
- }
- }
- int cango(LL x) {
- if(x == ) return ;
- int ok = ;
- for(int i = ; i <= ; ++i) {
- if(H[i] <= x) {
- cnt[i]--;
- if(cnt[i] < ) {
- ok = ;
- }
- }
- }
- if(ok) {
- for(int i = ; i <= ; ++i)
- if(H[i] <= x) cnt[i]++;
- return ;
- }
- else return ;
- }
- int can(LL now) {
- for(int i = G.size()-; i >= ; --i) {
- int ok = ;
- for(int j = ; j <= ; ++j) {
- if(G[i] <= H[j] && sum[j-]) {
- sum[j-]--;
- P[++cnts] = MP(j-,G[i]);
- ok = ;
- G.pop_back();
- break;
- }
- }
- if(!ok) return ;
- }
- return ;
- }
- int allcan(int x) {
- int j = x+,i = ;
- int ok;
- while(j <= cnts && i < G.size()) {
- if(P[j].second != ) j++;
- else if(H[P[j].first+] < G[i]) j++;
- else i++,j++;
- }
- if(i == G.size()) {
- return ;
- }
- else return ;
- }
- int check(int x) {
- x = cnts - x;
- if(x > cnts) return ;
- if(x == ) return ;
- G.clear();
- for(int i = ; i <= x; i++) {
- for(int j = ; j <= P[i].first; ++j) {
- G.push_back(H[j]);
- }
- if(P[i].second) {
- G.push_back(P[i].second);
- }
- }
- //for(int i = 0; i < G.size(); ++i) cout<<G[i]<<" ";cout<<endl;
- if(allcan(x)) {
- return ;
- }
- else return ;
- }
- int main() {
- H[] = ;
- for(int i = ; i <= ; ++i)H[i] = H[i-]*2LL;
- scanf("%d",&n);
- for(int i = ; i <= n; ++i) {
- scanf("%I64d",&a[i]);
- int ok = ;
- for(int j = ; j <= ; ++j) {
- if(a[i] == H[j]) {
- ok = ;
- cnt[j]++;
- break;
- }
- }
- if(!ok) G.push_back(a[i]);
- }
- int now = ;
- for(int i = ; i >=; --i) {
- while(cnt[i]) {
- if(cango(H[i])) {
- now++;
- sum[i]++;
- }
- else break;
- }
- }
- for(int i = ; i <= ; ++i)
- for(int j = ; j <= cnt[i]; ++j) G.push_back(H[i]);
- int l= ,r,ans = -,tmpr;
- if(can(now)) r = now;
- else r = -;
- tmpr = r;
- for(int i = ; i <= ; ++i) {
- for(int j = ; j <= sum[i]; ++j) {
- P[++cnts] = MP(i,);
- }
- }
- sort(P+,P+cnts+);
- while(l <= r) {
- int md = (l + r) >> ;
- if(check(md)) {
- ans = md;
- r = md-;
- }
- else l = md+;
- }
- //cout<<ans<<endl;
- if(tmpr == -) puts("-1");
- else {
- for(int i = ans; i <= tmpr; ++i) cout<<i<<" ";
- cout<<endl;
- }
- return ;
- }
- /*
- 5
- 1 2 3 4 5
- */
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