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  1. #include <bits/stdc++.h>
  2. #define ll long long
  3. #define el "\n"
  4. #define fast ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  5. #define __ROOT__ int main()
  6. #define fi first
  7. #define se second
  8. #define M 1000000007
  9. #define MAXN 10001
  10. #define GIOIHAN 1000001
  11. #define BLOCK_SIZE 425
  12. #define MAX_NODE 1001001
  13. #define ALPHA_SIZE 26
  14. #define compare(v) sort((v).begin(), (v).end()); (v).erase(unique((v).begin(), (v).end()), (v).end()); // dùng để nén sort mảng compare
  15. using namespace std;
  16. ll n,  m, mi, ma ,ans;
  17. ll sz[MAXN], par[MAXN]  ;
  18. struct Edge {
  19.     ll u, v, w ;
  20.     bool operator < (const Edge &other) const {
  21.        return w< other.w;
  22.     }
  23. } edge[MAXN];
  24. ll find_set(ll a ) {
  25.     if(par[a] == a) return a;
  26.     return par[a] =find_set(par[a]);
  27. }
  28. void uninon_set(ll a, ll b) {
  29.     a = find_set(a) ;
  30.     b = find_set(b);
  31.     if(a== b) return ;
  32.     if(sz[a] < sz[b]) swap(a,b) ;
  33.     sz[a] += sz[b] ;
  34.     par[b]=  a;
  35. }
  36. void init() {
  37.     cin>>n >> m ;
  38.     for(ll i =  0 ; i < m ;  i ++ ) {
  39.         cin>>edge[i].u >> edge[i].v >> edge[i].w;
  40.     }
  41.     sort(edge, edge+ m );
  42. //     for(ll i = 0 ; i  < m ;  i ++ ){
  43. //        cout<<edge[i].u<<" " << edge[i].v<< " "<< edge[i].w<<el ;
  44. //     }
  45. }
  46. void restart() {
  47.     for(ll i = 0  ; i  <= n ; i ++ ) par[i] = i,  sz[i] = 1;
  48. }
  49. ll check(ll l) {
  50.     restart() ;
  51.     ll cnt = 0;  mi = LONG_MAX,  ma=LONG_MIN  ;
  52.     for(ll i = l ;  i <m ; i ++ ) {
  53.         ll x= find_set(edge[i].u);
  54.         ll y= find_set(edge[i].v);
  55.         if(x != y ) {
  56.             cnt++ ;
  57.             uninon_set(x, y) ;
  58.             ma= max(edge[i].w,ma);
  59.             mi = min(edge[i].w,mi);
  60.               if(cnt == n- 1 ) return ma-mi;
  61.         }
  62.     }
  63.     return LONG_MAX ;
  64. }
  65. void solve() {
  66.      ans= LONG_MAX ;
  67.     for(ll i = 0 ; i < m ; i ++ ) {
  68.       ans = min(check(i) , ans );
  69. //      cout<< check(i)<<el;
  70.     }
  71.     if(ans == LONG_MAX) {
  72.         cout<<"NOT FOUND" ;
  73.     } else cout<<ans;
  74. }
  75.  
  76. __ROOT__ {
  77.     fast;
  78.     init();
  79.     solve();
  80. }
  81.  
Success #stdin #stdout 0s 5316KB
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Standard input is empty
stdout
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NOT FOUND
https://ideone.com/sT77Y1
language:
C++14 (gcc 8.3)
created:
1 day ago
visibility:
public

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