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IDProblemSubmitterResultTimeMemoryLanguageFile sizeSubmit timeJudge time
#403982#8211. Enumerating Substringsi_am_noob#AC ✓11ms9588kbC++142.0kb2024-05-03 01:29:332024-05-03 01:29:33

Judging History

你现在查看的是最新测评结果

  • [2024-05-03 01:29:33]
  • 评测
  • 测评结果:AC
  • 用时:11ms
  • 内存:9588kb
  • [2024-05-03 01:29:33]
  • 提交

answer

#include<bits/stdc++.h>
using namespace std;

using ll=long long;
using pii=pair<int,int>;
#define pb push_back
#define all(a) a.begin(),a.end()
#define sz(a) ((int)a.size())

const int N=2005,M=1000005,mod=1000000007;
int add(int x, int y){x+=y; if(x>=mod) x-=mod; return x;}
int sub(int x, int y){x-=y; if(x<0) x+=mod; return x;}
int mul(int x, int y){return 1ll*x*y%mod;}
int Pow(int x, ll y=mod-2){int res=1; for(; y; y>>=1,x=mul(x,x)) if(y&1) res=mul(res,x); return res;}

int n,m,k,pw[M],dp[N][N],fac[N],inv[N],ifac[N],kval[N],inv2[N];

signed main(){
    ios_base::sync_with_stdio(0),cin.tie(0);
    fac[0]=inv[1]=ifac[0]=1;
    for(int i=1; i<N; ++i) fac[i]=mul(fac[i-1],i);
    for(int i=2; i<N; ++i) inv[i]=mul(inv[mod%i],mod-mod/i);
    for(int i=1; i<N; ++i) ifac[i]=mul(ifac[i-1],inv[i]);
    inv2[0]=1,inv2[1]=Pow(2);
    for(int i=2; i<N; ++i) inv2[i]=mul(inv2[i-1],inv2[1]);
    cin >> n >> m >> k;
    pw[0]=1;
    for(int i=1; i<M; ++i) pw[i]=mul(pw[i-1],k);
    kval[0]=1;
    for(int i=1; i<N; ++i) kval[i]=mul(kval[i-1],k+1-i);
    int tot=0;
    for(int i=0; i*2<=m; ++i){
        int tmp=mul(mul(kval[m-i],fac[m]),mul(ifac[i],ifac[m-i*2]));
        tmp=mul(tmp,inv2[i]);
        tot=add(tot,tmp);
        //cout << tot << "\n";
    }

    int res=0;
    for(int x=1; x*2<=m; ++x){
        int de=0;
        for(int i=x; i*2<=m; ++i){
            int tmp=mul(mul(kval[m-i],fac[m-x*2]),mul(ifac[i-x],ifac[m-i*2]));
            //tmp=mul(mul(tmp,fac[i]),mul(ifac[i-x],ifac[x]));
            tmp=mul(tmp,inv2[i-x]);
            de=add(de,tmp);
        }
        //cout << x << ' ' << de << "\n";
        tot=sub(tot,de);
        for(int i=1; (i-1)*(m-x)+m<=n; ++i){
            if(i&1) res=add(res,mul(de,mul(pw[n-((i-1)*(m-x)+m)],n-((i-1)*(m-x)+m)+1)));
            else res=sub(res,mul(de,mul(pw[n-((i-1)*(m-x)+m)],n-((i-1)*(m-x)+m)+1)));
        }
    }
    res=add(res,mul(tot,mul(pw[n-m],n-m+1)));
    cout << res << "\n";
}

这程序好像有点Bug,我给组数据试试?

Details

Tip: Click on the bar to expand more detailed information

Test #1:

score: 100
Accepted
time: 6ms
memory: 9588kb

input:

4 2 3

output:

228

result:

ok 1 number(s): "228"

Test #2:

score: 0
Accepted
time: 10ms
memory: 7916kb

input:

999999 1999 12345678

output:

52352722

result:

ok 1 number(s): "52352722"

Test #3:

score: 0
Accepted
time: 5ms
memory: 7792kb

input:

7 4 2

output:

182

result:

ok 1 number(s): "182"

Test #4:

score: 0
Accepted
time: 3ms
memory: 8824kb

input:

4 3 4

output:

480

result:

ok 1 number(s): "480"

Test #5:

score: 0
Accepted
time: 5ms
memory: 7852kb

input:

3 1 1

output:

3

result:

ok 1 number(s): "3"

Test #6:

score: 0
Accepted
time: 3ms
memory: 8956kb

input:

5 5 1

output:

0

result:

ok 1 number(s): "0"

Test #7:

score: 0
Accepted
time: 2ms
memory: 7876kb

input:

7 4 3

output:

5784

result:

ok 1 number(s): "5784"

Test #8:

score: 0
Accepted
time: 6ms
memory: 8140kb

input:

5 2 4

output:

3932

result:

ok 1 number(s): "3932"

Test #9:

score: 0
Accepted
time: 5ms
memory: 7900kb

input:

8 2 2

output:

1522

result:

ok 1 number(s): "1522"

Test #10:

score: 0
Accepted
time: 5ms
memory: 8472kb

input:

8 1 2

output:

2048

result:

ok 1 number(s): "2048"

Test #11:

score: 0
Accepted
time: 3ms
memory: 8992kb

input:

7 5 3

output:

2430

result:

ok 1 number(s): "2430"

Test #12:

score: 0
Accepted
time: 5ms
memory: 8044kb

input:

10 4 3

output:

272004

result:

ok 1 number(s): "272004"

Test #13:

score: 0
Accepted
time: 10ms
memory: 7652kb

input:

675978 614 2

output:

0

result:

ok 1 number(s): "0"

Test #14:

score: 0
Accepted
time: 7ms
memory: 9268kb

input:

244613 38 1

output:

0

result:

ok 1 number(s): "0"

Test #15:

score: 0
Accepted
time: 3ms
memory: 8656kb

input:

186293 1462 1

output:

0

result:

ok 1 number(s): "0"

Test #16:

score: 0
Accepted
time: 6ms
memory: 8380kb

input:

24867 886 1

output:

0

result:

ok 1 number(s): "0"

Test #17:

score: 0
Accepted
time: 11ms
memory: 8292kb

input:

976164 1014 2

output:

0

result:

ok 1 number(s): "0"

Test #18:

score: 0
Accepted
time: 6ms
memory: 8552kb

input:

179356 2 716844809

output:

577866092

result:

ok 1 number(s): "577866092"

Test #19:

score: 0
Accepted
time: 9ms
memory: 9256kb

input:

621001 130 310625363

output:

892869197

result:

ok 1 number(s): "892869197"

Test #20:

score: 0
Accepted
time: 9ms
memory: 7860kb

input:

678862 850 754662812

output:

582264789

result:

ok 1 number(s): "582264789"

Test #21:

score: 0
Accepted
time: 9ms
memory: 7860kb

input:

650845 978 348443366

output:

825425732

result:

ok 1 number(s): "825425732"

Test #22:

score: 0
Accepted
time: 4ms
memory: 8396kb

input:

669914 402 87448112

output:

318098088

result:

ok 1 number(s): "318098088"

Test #23:

score: 0
Accepted
time: 10ms
memory: 8132kb

input:

998593 530 681228665

output:

408255654

result:

ok 1 number(s): "408255654"

Test #24:

score: 0
Accepted
time: 6ms
memory: 8112kb

input:

369361 1954 125266115

output:

509912384

result:

ok 1 number(s): "509912384"

Test #25:

score: 0
Accepted
time: 7ms
memory: 8604kb

input:

900226 1378 424079373

output:

406320917

result:

ok 1 number(s): "406320917"

Test #26:

score: 0
Accepted
time: 8ms
memory: 7844kb

input:

334887 1506 17859926

output:

503264679

result:

ok 1 number(s): "503264679"

Test #27:

score: 0
Accepted
time: 11ms
memory: 8404kb

input:

936048 544 53978328

output:

548647866

result:

ok 1 number(s): "548647866"

Test #28:

score: 0
Accepted
time: 7ms
memory: 7816kb

input:

152789 1264 792983073

output:

839541707

result:

ok 1 number(s): "839541707"

Test #29:

score: 0
Accepted
time: 11ms
memory: 9356kb

input:

714493 1392 91796331

output:

721071046

result:

ok 1 number(s): "721071046"

Test #30:

score: 0
Accepted
time: 7ms
memory: 9540kb

input:

269571 816 830801077

output:

330064211

result:

ok 1 number(s): "330064211"

Test #31:

score: 0
Accepted
time: 10ms
memory: 9120kb

input:

845120 944 424581630

output:

348960190

result:

ok 1 number(s): "348960190"

Test #32:

score: 0
Accepted
time: 8ms
memory: 8164kb

input:

533990 368 163586376

output:

522092095

result:

ok 1 number(s): "522092095"

Test #33:

score: 0
Accepted
time: 8ms
memory: 7952kb

input:

181707 1792 462399634

output:

373795106

result:

ok 1 number(s): "373795106"

Test #34:

score: 0
Accepted
time: 10ms
memory: 8820kb

input:

417349 1920 761212891

output:

587051329

result:

ok 1 number(s): "587051329"

Test #35:

score: 0
Accepted
time: 9ms
memory: 9316kb

input:

526583 1344 500217637

output:

108767800

result:

ok 1 number(s): "108767800"

Test #36:

score: 0
Accepted
time: 7ms
memory: 8788kb

input:

867054 769 93998191

output:

239123369

result:

ok 1 number(s): "239123369"

Extra Test:

score: 0
Extra Test Passed