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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define fast ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL)
  4. #define mofile(s) freopen(s,"r",stdin)
  5. #define outfile(s) freopen(s,"w",stdout)
  6. #define ll long long
  7. #define ii pair<ll,ll>
  8. #define iii pair<ll,ii>
  9. #define fi first
  10. #define se second
  11. #define tf bool
  12. #define ST stack
  13. #define Q deque
  14. #define Q queue
  15. #define S string
  16. #define Ma map
  17. #define UM unormideremid_map
  18. #define SE set
  19. #define str(x) to_string(x)
  20. #define all(a) (a).begin(),(a).end()
  21. #define FOR(i,l,r,mid) for(int i=l;i<=r;i+=mid)
  22. #define FOD(i,l,r,mid) for(int i=r;i>=l;i-=mid)
  23. #define xuong cout<<"\n"
  24. #define midebug(x) cout<<(x)<<" "
  25. #define ppcnt(x) __builtin_popcountll(x)
  26. #define parity(x) __builtin_parityll(x)
  27. #define leamid0(x) __builtin_clzll(x)
  28. #define LOG2 __lg(x)
  29. #define tr0(x) __builtin_ctzll(x)
  30. #define fiset(x) __builtin_ffsll(x)
  31. #define MASK(k) (1LL<<(k))
  32. #define BIT(x,k) ((x)>>(k)&1)
  33. #define pb push_back
  34. #define tron(x) setprecision(x)
  35. #define het return 0
  36. #define base_ 1000000000
  37. template<typename... T>
  38. void in(T&... args) { ((cin >> args), ...); }
  39. template<class X, class Y>
  40. bool maximize(X &x, const Y &y){return (x < y) ? x = y, 1 : 0;}
  41. template<class X, class Y>
  42. bool minimize(X &x, const Y &y){return (x > y) ? x = y, 1 : 0;}
  43. const int maxn=1e6+5;
  44. const ll tle=2e8;
  45. const ll INF=1e9+9;
  46. const int base=31;
  47. const ll MOD=2026;
  48. string bcc="abcmidefghijklmnopqrstuvwxyz";
  49. int midx[]={-1,0,1,0};
  50. int midy[]={0,1,0,-1};
  51. bool sang[10000005];
  52. ll pref[1005][1005],mt[1005][1005];
  53. void sieve(){
  54. for(int i=1;i<=10000000;++i) sang[i]=1;
  55. sang[0]=sang[1]=0;
  56. for(int i=2;i*i<=10000000;++i){
  57. if(sang[i]){
  58. for(int j=i*i;j<=10000000;j+=i) sang[j]=0;
  59. }
  60. }
  61. }
  62. void lis(){
  63. vector<int>t;
  64. vector<int>a;
  65. int n; cin>>n;
  66. for(int i=1;i<=n;++i){
  67. int ai; cin>>ai;
  68. a.pb(ai);
  69. }
  70. for(int x:a){
  71. auto it=lower_bound(all(t),x);
  72. if(it==t.end()) t.pb(x);
  73. else *it=x;
  74. }
  75. }
  76. void pfs2mid(){
  77. int n,m,k; cin>>n>>k; m=n;
  78. for(int i=1;i<=n;++i){
  79. for(int j=1;j<=m;++j) cin>>mt[i][j];
  80. }
  81. for(int i=1;i<=n;++i){
  82. for(int j=1;j<=m;++j) pref[i][j]=mt[i][j]+pref[i-1][j]+pref[i][j-1]-pref[i-1][j-1];
  83. }
  84. }
  85. ll qu2mid(int x1,int y1,int x2,int y2){
  86. return pref[x2][y2]-pref[x1-1][y2]-pref[x2][y1-1]+pref[x1-1][y1-1];
  87. }
  88. void open(){
  89. if(fopen("mideptrai.INP","r")){
  90. mofile("mideptrai.INP");
  91. outfile("mideptrai.OUT");
  92. }
  93. }
  94. int n;
  95. vector<ll> a1,a2;
  96. ll inp[41],ans=-1,sum,mod=1e9;
  97. void sinhtongcon(int i,int r,ll s,vector<ll> &a){
  98. if(i>r) a.pb(s%mod);
  99. else{
  100. sinhtongcon(i+1,r,s,a);
  101. sinhtongcon(i+1,r,(s+inp[i])%mod,a);
  102. }
  103. }
  104. int main(){
  105. fast;
  106. cin>>n;
  107. for(int i=1;i<=n;++i) cin>>inp[i];
  108. sinhtongcon(1,n/2,0,a1);
  109. sinhtongcon(n/2+1,n,0,a2);
  110. sort(a1.begin(),a1.end());
  111. sort(a2.begin(),a2.end());
  112. int vt1=0,n1=a1.size(),vt2=a2.size()-1;
  113. int mx=a2[vt2];
  114. while(vt1<n1 && vt2>=0){
  115. if(a1[vt1]+a2[vt2]>=mod) --vt2;
  116. else ans=max(ans,max((a1[vt1]+mx)%mod,a1[vt1]+a2[vt2])),++vt1;
  117. }
  118. cout<<ans;
  119. het;
  120. }
  121.  
Success #stdin #stdout 0s 5304KB
stdin
3
1000000000 1000000000 6
stdout
6