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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 DQ 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 ll maxn=1e6+5;
  44. const ll tle=2e8;
  45. const ll INF=1e9+9;
  46. const int base=31;
  47. const ll MOD=1e9+7;
  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. const int M=1e9+7;
  95. long long p(long long a,long long b){
  96.     long long r=1;
  97.     a%=M;
  98.     while(b>0){
  99.         if(b%2==1)r=(r*a)%M;
  100.         a=(a*a)%M;
  101.         b/=2;
  102.     }
  103.     return r;
  104. }
  105. long long inv(long long n){
  106.     return p(n,M-2);
  107. }
  108. void solve(){
  109.     long long n,k; cin>>n>>k;
  110.     if(k>n){
  111.         cout<<0<<"\n";
  112.         return;
  113.     }
  114.     if(k==0){
  115.         cout<<1<<"\n";
  116.         return;
  117.     }
  118.     long long u=1,v=1;
  119.     for(int i=0;i<k;++i){
  120.         u=(u*((n-i)%M))%M;
  121.         v=(v*(i+1))%M;
  122.     }
  123.     cout<<(u*inv(v))%M<<"\n";
  124. }
  125. int main(){
  126.     fast;
  127.     int q; cin>>q;
  128.     while(q--)solve();
  129.     het;
  130. }
  131.  
Success #stdin #stdout 0s 5316KB
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https://ideone.com/R2Hr0J
language:
C++ (gcc 8.3)
created:
14 hours ago
visibility:
public

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