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  • Codeforces Round #412 (rated, Div. 2, base on VK Cup 2017 Round 3) E. Prairie Partition 二分+贪心

    E. Prairie Partition

    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!

    Input

    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

    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.

    Examples
    input
    8
    1 1 2 2 3 4 5 8
    output
    2 
    Note

    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+10, M = 1e3+20, mod = 1e9+7,inf = 2e9;
    
    LL H[70],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 = 0; i <= 60; ++i) {
            if(x < H[i])
                break;
        }
        i--;
        for(int j = 0; j <= i; ++j) {
            cnt[j]--;
            if(cnt[j] < 0) No = 1;
            return ;
        }
    }
    int cango(LL x) {
        if(x == 0) return 0;
        int ok = 0;
        for(int i = 0; i <= 60; ++i) {
            if(H[i] <= x) {
                cnt[i]--;
                if(cnt[i] < 0) {
                    ok = 1;
                }
            }
        }
        if(ok) {
           for(int i = 0; i <= 60; ++i)
                if(H[i] <= x) cnt[i]++;
            return 0;
        }
        else return 1;
    }
    int can(LL now) {
        for(int i = G.size()-1; i >= 0; --i) {
            int ok = 0;
            for(int j = 1; j <= 60; ++j) {
                if(G[i] <= H[j] && sum[j-1]) {
                    sum[j-1]--;
                    P[++cnts] = MP(j-1,G[i]);
                    ok = 1;
                    G.pop_back();
                    break;
                }
            }
            if(!ok) return 0;
        }
        return 1;
    }
    int allcan(int x) {
        int j = x+1,i = 0;
        int ok;
        while(j <= cnts && i < G.size()) {
            if(P[j].second  != 0) j++;
            else if(H[P[j].first+1] < G[i]) j++;
            else i++,j++;
        }
        if(i == G.size()) {
            return 1;
        }
        else return 0;
    }
    int check(int x) {
        x = cnts - x;
        if(x > cnts) return 0;
        if(x == 0) return 1;
        G.clear();
        for(int i = 1; i <= x; i++) {
            for(int j = 0; 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 1;
        }
        else return 0;
    }
    int main() {
        H[0] = 1;
        for(int i = 1; i <= 60; ++i)H[i] = H[i-1]*2LL;
        scanf("%d",&n);
        for(int i = 1; i <= n; ++i) {
            scanf("%I64d",&a[i]);
            int ok = 0;
            for(int j = 0; j <= 60; ++j) {
                if(a[i] == H[j]) {
                    ok = 1;
                    cnt[j]++;
                    break;
                }
            }
            if(!ok) G.push_back(a[i]);
        }
        int now = 0;
        for(int i = 60; i >=0; --i) {
            while(cnt[i]) {
                if(cango(H[i])) {
                 now++;
                 sum[i]++;
                }
                else break;
            }
        }
        for(int i = 0; i <= 60; ++i)
            for(int j = 1; j <= cnt[i]; ++j) G.push_back(H[i]);
        int l= 1,r,ans = -1,tmpr;
        if(can(now)) r = now;
        else r = -1;
        tmpr = r;
        for(int i = 0; i <= 60; ++i) {
            for(int j = 1; j <= sum[i]; ++j) {
                P[++cnts] = MP(i,0);
            }
        }
        sort(P+1,P+cnts+1);
        while(l <= r) {
            int md = (l + r) >> 1;
            if(check(md)) {
                ans = md;
                r = md-1;
            }
            else l = md+1;
        }
        //cout<<ans<<endl;
        if(tmpr == -1) puts("-1");
        else {
            for(int i = ans; i <= tmpr; ++i) cout<<i<<" ";
            cout<<endl;
        }
        return 0;
    }
    /*
    5
    1 2 3 4 5
    */
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  • 原文地址:https://www.cnblogs.com/zxhl/p/6827038.html
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