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  1. // ඞඞඞඞඞඞ you sus
  2. #include <bits/stdc++.h>
  3.  
  4. #define __builtin_popcount __builtin_popcountll
  5. #define BIT(x, i) (((x)>> (i))& 1)
  6. #define MASK(x) (1LL<< (x))
  7. #define sqr(x) ((x)* (x))
  8. #define MOD 1000000007
  9. #define template(i) for(long long i= 1; i<= n; i++)
  10.  
  11. using namespace std;
  12.  
  13. typedef long long ll;
  14.  
  15. template<class X,class Y>
  16.     void minimize(X &x,const Y y) {
  17.         if (x>y) x= y;
  18.     }
  19. template<class X,class Y>
  20.     void maximize(X &x,const Y y) {
  21.         if (x<y) x= y;
  22.     }
  23. template<class T>
  24.     T Abs(const T x) {
  25.         return (x<0?-x:x);
  26.     }
  27.  
  28. template <class T>
  29.     void Mod(T &t) {
  30.         if(t>= MOD) t-= MOD;
  31.     }
  32.  
  33. template <class X, class Y>
  34.     ll Gcd(const X a, const Y b){
  35.         if(b== 0)   return a;
  36.         else return Gcd(b, a% b);
  37.     }
  38.  
  39. template <class X, class Y>
  40.     ll Lcm(const X a, const Y b){
  41.         return ((a*b)/gcd(a, b));
  42.     }
  43.  
  44. template <class X, class Y>
  45.     void Add(X &x, const Y y){
  46.         if((x+= y)>= MOD) x-= MOD;
  47.     }
  48.  
  49. const int maxm= (int)1e6+ 3, maxn= (int)1e5 +3, maxpst= (int)17e5, maxb= (int)1e3+ 3;
  50.  
  51. const ll INF= (ll)1e18+ 3;
  52.  
  53. vector<ll> adj[maxb];
  54.  
  55. vector<ll> topo;
  56. ll n, a[maxb], f[maxb], ans= 0, vis[maxb];
  57.  
  58. void Dfs(ll u){
  59.     vis[u]= 1;
  60.     for(long long i= 0; i< adj[u].size(); i++){
  61.         ll v= adj[u][i];
  62.         if(!vis[v])
  63.             Dfs(v);
  64.     }
  65.     topo.push_back(u);
  66. }
  67.  
  68. void printans(){
  69.     cout<< ans;
  70. }
  71.  
  72. void solve(){
  73.     for(int i= 1; i<= n; i++){
  74.         for(int j= 1; j<= n; j++){
  75.             for(int k= 1; k<= n; k++){
  76.                 if((i== j)|| (i== k)|| (j== k)) continue;
  77.                 if(a[i]+ a[j]== a[k]){
  78.                     adj[i].push_back(k);
  79.                     adj[j].push_back(k);
  80.                 }
  81.             }
  82.         }
  83.     }
  84.     for(long long i= 1; i<= n; i++){
  85.         if(vis[i]== 0){
  86.             Dfs(i);
  87.         }
  88.     }
  89.     reverse(topo.begin(), topo.end());
  90.     for(long long i= 1; i<= n; i++){
  91.         f[i]= 1;
  92.     }
  93.     for(long long i= 0; i< n; i++){
  94.         ll u= topo[i];
  95.         for(long long j= 0; j< adj[u].size(); j++){
  96.             ll v= adj[u][j];
  97.             maximize(f[v], f[u]+ 1);
  98.         }
  99.         maximize(ans, f[u]);
  100.     }
  101. }
  102.  
  103. void input(){
  104.     cin>> n;
  105.     for(long long i= 1; i<= n; i++){
  106.         cin>> a[i];
  107.     }
  108.     solve();
  109.     printans();
  110. }
  111.  
  112. int main()
  113.  
  114. {   ios_base::sync_with_stdio(0);cin.tie(0);
  115.     #define task ""
  116.     if(fopen(task".inp", "r")){
  117.         freopen(task".inp", "r", stdin);
  118.         freopen(task".out", "w", stdout);
  119.     }
  120.     if(fopen("task.inp", "r")){
  121.         freopen("task.inp", "r", stdin);
  122.         freopen("task.out", "w", stdout);
  123.     }
  124.     input();
  125.     return 0;
  126. }
  127.  
Success #stdin #stdout 0s 5284KB
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https://ideone.com/YO6S3m
language:
C++14 (gcc 8.3)
created:
8 hours ago
visibility:
public

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