2018.6.4（map进阶----codeforces C. Equal Sums）

本文提供了一种解决CodeForces 988/C问题的方法，通过使用C++中的map来存储中间结果，并利用嵌套数据结构进行快速查找，从而判断是否存在符合条件的两个序列。文章中的代码展示了如何有效地组织数据和利用标准库函数来简化复杂度。

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http://codeforces.com/contest/988/problem/C

以下代码拷贝大神代码

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
#include<cmath>
#include<vector>
#include<set>
#include<queue>
#include<limits.h>
#include<string.h>
#include<map>
#include<list>
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;

#define inf int(0x3f3f3f3f)
#define mod int(1e9+7)
#define eps double(1e-6)
#define pi acos(-1.0)
#define lson  root << 1
#define rson  root << 1 | 1



map< int,pair<int ,int> >mmp;

map< int ,pair<int,int> >::iterator it;

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int zu;
    mmp.clear();
    cin>>zu;
    for(int t=1;t<=zu;t++)
    {
        int n;
        cin>>n;
        vector<int> v;
        int sum=0;
        int x;
        for(int i=0;i<n;i++)
            cin>>x,v.push_back(x),sum+=x;
        for(int i=0;i<n;i++)
        {
            int ans=sum-v[i];
            if(t!=1)
            {
                it=mmp.lower_bound(ans);
                if(it!=mmp.end()&&it->first==ans&&it->second.first!=t)//嵌套map中的定义成pair<int ,int >才有first与second成员；如果定义成map<int ,int >编译报错
                {
                    cout<<"YES"<<endl;
                    cout<<it->second.first<<" "<<it->second.second<<endl;
                    cout<<t<<" "<<i+1<<endl;
                    return 0;
                }

            }
            mmp[ans]=make_pair(t,i+1);
        }
    }
    cout<<"NO"<<endl;
}

map的默认排序和自定义排序
https://www.cnblogs.com/stay-alive/p/8215400.html

stl map中的lower_bound和upper_bound
http://www.cnblogs.com/billin/archive/2011/09/01/2162102.html

C++中的map嵌套应用
https://blog.youkuaiyun.com/computer055maxi/article/details/6055427

//待理解


 #include <bits/stdc++.h>
#define fst first
#define snd second
#define fore(i,a,n) for(int i=a;i<n;i++)
#define pb push_back
#define mp make_pair
#define ALL(s) s.begin(),s.end()
#define FIN ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0)
using namespace std;
typedef pair<int,int> ii;
typedef long long ll;

map<ll,vector<ii> > m;
int n,a[200500];
int main() {FIN;
    cin>>n;
    fore(i,0,n) {
        int k; cin>>k;
        ll s=0;
        fore(j,0,k)cin>>a[j],s+=a[j];
        fore(j,0,k) m[s-a[j]].pb(ii(i+1,j+1));
    }
    for(pair<ll,vector<ii> > u:m) {
        sort(ALL(u.snd));
        fore(i,0,u.snd.size()-1) if(u.snd[i].fst!=u.snd[i+1].fst) {
            ii p=u.snd[i],q=u.snd[i+1];
            cout<<"YES\n"<<p.fst<<" "<<p.snd<<"\n"<<q.fst<<" "<<q.snd<<"\n";
            return 0;
        }
    }
    cout<<"NO"<<"\n";
}


#include <iostream>
#include <vector>
#include <cmath>
#include <algorithm>
#include <map>
#include <set>
#include <string>
#include <queue>

// watsonlee Coding

using namespace std;

#define ll long long 

int main() {
    ll k;
    cin >> k;
    vector<vector<ll>> vec;
    map <ll, set<ll>> mp;
    for (ll j = 0; j < k; j++) {
        ll n;
        cin >> n;
        vector <ll> vect;
        for (ll i = 0; i < n; i++) {
            ll a;
            cin >> a;
            vect.push_back(a);
        }
        vec.push_back(vect);
    }
    for (ll j = 0; j < k; j++) {
        ll sum = 0;
        for (ll i = 0; i < vec[j].size(); i++) {
            sum += vec[j][i];
        }
        for (ll i = 0; i < vec[j].size(); i++) {
            mp[sum - vec[j][i]].insert(j);
        }
    }
    map <ll, set<ll>> ::iterator it = mp.begin();
    bool flag = false;
    for (; it != mp.end() && !flag; it++) {
        if (it->second.size() >= 2) {
            set <ll> ::iterator st = it->second.begin();
            ll a, b;
            a = *st;
            st++;
            b = *st;
            cout << "YES" << endl;
            cout << a + 1 << " ";
            ll sum = 0;
            for (ll j = 0; j < vec[a].size(); j++) {
                sum += vec[a][j];
            }
            for (ll j = 0; j < vec[a].size(); j++) {
                if (it->first == sum - vec[a][j]) {
                    cout << j + 1 << endl;
                    break;
                }
            }
            sum = 0;
            cout << b + 1 << " ";
            for (ll j = 0; j < vec[b].size(); j++) {
                sum += vec[b][j];
            }
            for (ll j = 0; j < vec[a].size(); j++) {
                if (it->first == sum - vec[b][j]) {
                    cout << j + 1 << endl;
                    break;
                }
            }
            flag = true;
        }
    }
    if (!flag) {
        cout << "NO";
    }
    return 0;
}