• Codeforces Round #486 (Div. 3) CD


    C. Equal Sums

    You are given kk sequences of integers. The length of the ii-th sequence equals to nini.

    You have to choose exactly two sequences ii and jj (iji≠j) such that you can remove exactly one element in each of them in such a way that the sum of the changed sequence ii (its length will be equal to ni1ni−1) equals to the sum of the changed sequence jj (its length will be equal to nj1nj−1).

    Note that it's required to remove exactly one element in each of the two chosen sequences.

    Assume that the sum of the empty (of the length equals 00) sequence is 00.

    Input

    The first line contains an integer kk (2k21052≤k≤2⋅105) — the number of sequences.

    Then kk pairs of lines follow, each pair containing a sequence.

    The first line in the ii-th pair contains one integer nini (1ni<21051≤ni<2⋅105) — the length of the ii-th sequence. The second line of the ii-th pair contains a sequence of nini integers ai,1,ai,2,,ai,niai,1,ai,2,…,ai,ni.

    The elements of sequences are integer numbers from 104−104 to 104104.

    The sum of lengths of all given sequences don't exceed 21052⋅105, i.e. n1+n2++nk2105n1+n2+⋯+nk≤2⋅105.

    Output

    If it is impossible to choose two sequences such that they satisfy given conditions, print "NO" (without quotes). Otherwise in the first line print "YES" (without quotes), in the second line — two integers ii, xx (1ik,1xni1≤i≤k,1≤x≤ni), in the third line — two integers jj, yy (1jk,1ynj1≤j≤k,1≤y≤nj). It means that the sum of the elements of the ii-th sequence without the element with index xx equals to the sum of the elements of the jj-th sequence without the element with index yy.

    Two chosen sequences must be distinct, i.e. iji≠j. You can print them in any order.

    If there are multiple possible answers, print any of them.

    Examples
    input
    Copy
    2
    5
    2 3 1 3 2
    6
    1 1 2 2 2 1
    output
    Copy
    YES
    2 6
    1 2
    input
    Copy
    3
    1
    5
    5
    1 1 1 1 1
    2
    2 3
    output
    Copy
    NO
    input
    Copy
    4
    6
    2 2 2 2 2 2
    5
    2 2 2 2 2
    3
    2 2 2
    5
    2 2 2 2 2
    output
    Copy
    YES
    2 2
    4 1
    Note

    In the first example there are two sequences [2,3,1,3,2][2,3,1,3,2] and [1,1,2,2,2,1][1,1,2,2,2,1]. You can remove the second element from the first sequence to get [2,1,3,2][2,1,3,2] and you can remove the sixth element from the second sequence to get [1,1,2,2,2][1,1,2,2,2]. The sums of the both resulting sequences equal to 88, i.e. the sums are equal.

    任选两个序列,两个序列都除去他们中的一个数,使的总和相同。

    因为总和的数量不超过2e5   所以能全部用结构体保存。 有三个值。

    假设第i个序列,第j个数。  那么sum是第i个序列总和减去第j个数的值,id是第几个数。kk是第几个序列。

    那么排下序,找到相同的sum,然后在找不同的kk  存在就是YES 或者就是 NO。

     1 #include <bits/stdc++.h>
     2 #define ll long long
     3 using namespace std;
     4 const int N = 2e5+10;
     5 ll k, len, x;
     6 struct Nod{
     7     ll sum, id, kk;
     8     Nod() {
     9         id = kk = sum = -1;
    10     }
    11 }nod[N];
    12 ll a[N];
    13 bool cmp(const Nod &a, const Nod &b) {
    14     if(a.sum != b.sum ) return a.sum < b.sum;
    15     else return a.kk < b.kk;
    16 }
    17 int main() {
    18     int n = 0;
    19     scanf("%lld", &k);
    20     for(int i = 1; i <= k; i ++) {
    21         scanf("%lld", &len);
    22         ll sum = 0;
    23         for(int j = 1; j <= len; j ++) {
    24             scanf("%lld", &a[j]);
    25             sum += a[j];
    26         }
    27         for(int j = 1; j <= len; j ++) {
    28             nod[n].sum = sum - a[j];
    29             nod[n].kk = i;
    30             nod[n++].id = j;
    31         }
    32     }
    33     sort(nod,nod+n,cmp);
    34     // for(int i = 0; i < n; i ++) {
    35     //     printf("%lld %lld %lld
    ",nod[i].sum,nod[i].kk,nod[i].id);
    36     // }
    37     int l = 0, r = 1;
    38     while(r < n) {
    39         while(nod[l].sum != nod[r].sum && r+1 < n) {
    40             l++;r++;
    41         }
    42         while(nod[l].sum == nod[r].sum && nod[r].sum == nod[r+1].sum) r++;
    43         if(nod[l].sum == nod[r].sum && nod[l].kk != nod[r].kk) {
    44             printf("YES
    ");
    45             return 0*printf("%lld %lld
    %lld %lld
    ",nod[l].kk,nod[l].id,nod[r].kk,nod[r].id);
    46         }
    47         r += 2;
    48         l = r - 1;
    49     }
    50     printf("NO
    ");
    51     return 0;
    52 }

    D. Points and Powers of Two

    standard output

    There are nn distinct points on a coordinate line, the coordinate of ii-th point equals to xixi. Choose a subset of the given set of points such that the distance between each pair of points in a subset is an integral power of two. It is necessary to consider each pair of points, not only adjacent. Note that any subset containing one element satisfies the condition above. Among all these subsets, choose a subset with maximum possible size.

    In other words, you have to choose the maximum possible number of points xi1,xi2,,ximxi1,xi2,…,xim such that for each pair xijxij, xikxik it is true that |xijxik|=2d|xij−xik|=2d where dd is some non-negative integer number (not necessarily the same for each pair of points).

    Input

    The first line contains one integer nn (1n21051≤n≤2⋅105) — the number of points.

    The second line contains nn pairwise distinct integers x1,x2,,xnx1,x2,…,xn (109xi109−109≤xi≤109) — the coordinates of points.

    Output

    In the first line print mm — the maximum possible number of points in a subset that satisfies the conditions described above.

    In the second line print mm integers — the coordinates of points in the subset you have chosen.

    If there are multiple answers, print any of them.

    Examples
    input
    Copy
    6
    3 5 4 7 10 12
    output
    Copy
    3
    7 3 5
    input
    Copy
    5
    -1 2 5 8 11
    output
    Copy
    1
    8
    Note

    In the first example the answer is [7,3,5][7,3,5]. Note, that |73|=4=22|7−3|=4=22, |75|=2=21|7−5|=2=21 and |35|=2=21|3−5|=2=21. You can't find a subset having more points satisfying the required property.

     选取最大的区间,使的两两之差是2d ,d是非负整数。可以得出一个结论,最大的子集不会超过3个。

     1 #include <bits/stdc++.h>
     2 using namespace std;
     3 const int N = 2e5+10;
     4 int a[N], n;
     5 map<int,int> mp;
     6 int main() {
     7     scanf("%d",&n);
     8     for(int i = 0; i < n; i ++) {
     9         scanf("%d",&a[i]);
    10         mp[a[i]] = 1;
    11     }
    12     sort(a,a+n);
    13     for(int i = 0; i < n; i ++) {
    14         for(int j = 0; j < 32; j ++) {
    15             int x = 1 << j;
    16             if(mp[a[i]+x] && mp[a[i]+2*x]) {
    17                 return 0*printf("3
    %d %d %d
    ",a[i],a[i]+x,a[i]+x*2);
    18             }
    19             if(a[i]+x > a[n-1] || a[i]+2*x > a[n-1]) break;
    20         }
    21     }
    22     for(int i = 0; i < n; i ++) {
    23         for(int j = 0; j < 32; j ++) {
    24             int x = 1 << j;
    25             if(mp[a[i]+x]) {
    26                 return 0*printf("2
    %d %d
    ",a[i],a[i]+x);
    27             }
    28             if(mp[a[i]+x*2]) {
    29                 return 0*printf("2
    %d %d
    ",a[i],a[i]+2*x);
    30             }
    31             if(a[i]+x > a[n-1] || a[i]+2*x > a[n-1]) break;
    32         }
    33     }
    34     printf("1
    %d
    ",a[0]);
    35     return 0;
    36 }
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  • 原文地址:https://www.cnblogs.com/xingkongyihao/p/9124635.html
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