Codeforces 988C(STL运用)
题面:
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 (i≠ji≠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 ni−1ni−1) equals to the sum of the changed sequence jj (its length will be equal to nj−1nj−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.
The first line contains an integer kk (2≤k≤2⋅1052≤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 (1≤ni<2⋅1051≤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 2⋅1052⋅105, i.e. n1+n2+⋯+nk≤2⋅105n1+n2+⋯+nk≤2⋅105.
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 (1≤i≤k,1≤x≤ni1≤i≤k,1≤x≤ni), in the third line — two integers jj, yy (1≤j≤k,1≤y≤nj1≤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. i≠ji≠j. You can print them in any order.
If there are multiple possible answers, print any of them.
2 5 2 3 1 3 2 6 1 1 2 2 2 1
YES 2 6 1 2
3 1 5 5 1 1 1 1 1 2 2 3
NO
4 6 2 2 2 2 2 2 5 2 2 2 2 2 3 2 2 2 5 2 2 2 2 2
YES 2 2 4 1
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.
题目描述:
给你k个序列,第i个序列有ni个数。问你是否可以存在两个序列i和序列j,使得在第i个序列和第j个序列中分别删除1个数,使得他们的和相等。
题目分析:
这个题算是一个stl的综合运用的题目。
首先我们会发现,k个序列每个序列n个数,那么最大我们需要存4e10个数。然而普通的数组是存不下这么多的。因此,在这个题中,我们只能选择使用stl中的vector进行数的存储。
因为我们要求的是要删除哪一个序列的哪一个数,因此,我们对每一个序列中的数进行枚举,记录总的值sum减去该个数ai的值,将所得到的数记录到一个map中。倘若这个值已经在map中已经出现过了,则证明之前也曾统计过,因此直接输出答案即可。
而倘若这个值并没有在map中出现过,则我们须将这个值打上标记,同时再用两个map分别记录下这次删除的是第几个序列的第几个数即可。
ps:因为在这个题中,所给的数值是可能存在负数的,因此如果直接开数组当桶的话会导致RE,因此在这个题中,只能够使用map去记录!!
代码:
#include <bits/stdc++.h>
#define maxn 200005
using namespace std;
typedef long long ll;
vector<ll>vec[maxn];
map<ll,int>bag1;
map<ll,int>bag2;
map<ll,int>bag3;
int main()
{
int k;
scanf("%d",&k);
ll sum=0;
for(int i=1;i<=k;i++){
int n;
scanf("%d",&n);
sum=0;
for(int j=0;j<n;j++){
ll num;
cin>>num;
vec[i].push_back(num);
sum+=vec[i][j];
}
for (int j=0;j<n;j++){
ll tmp=sum-vec[i][j];
if (bag1[tmp]){
if(bag2[tmp]==i) continue;
else{
puts("YES");
printf("%d %d\n",i,j+1);
cout<<bag2[tmp]<<" "<<bag3[tmp]<<endl;
}
}
else{
bag1[tmp]=1;
bag2[tmp]=i;
bag3[tmp]=j+1;
}
}
}
puts("NO");
return 0;
}