2019hdu多校1
1009
考虑贪心,暴力枚举一位。
$o(676n)$
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
#include<bits/stdc++.h> using namespace std; const int N=1e5+333; int n,m,zl; int pos[26],cnt[N],t[26],az[N]; char s[N],st[N]; int l[N],r[N],nx[N],zzq[26]; int main(){ ios::sync_with_stdio(0); //freopen("p.in","r",stdin); //freopen("p.out","w",stdout); while(cin>>s){ n=strlen(s); cin>>m; for(int i=0;i<26;i++)cin>>l[i]>>r[i]; //if(m>10)continue; int ans=0; for(int i=0;i<=25;i++){ans+=l[i];pos[i]=n+3;t[i]=0;cnt[n+3]=0;} for(int i=0;i<=n+20;i++)az[i]=cnt[i]=0; for(int i=n;i>=1;i--){ int dot=s[i-1]-'a'; nx[i]=pos[dot]; pos[dot]=i; t[dot]++; cnt[i]=t[dot]; } zl=0; /*while(pos[0]<=n){ cout<<pos[0]<<g' '<<cnt[pos[0]]<<endl; pos[0]=nx[pos[0]]; }*/ for(int i=1;i<=m;i++){ st[i-1]='0'; for(int j=0;j<=25;j++){ int len=n-pos[j]; if(len+i<m)continue; if(az[j]==r[j])continue; bool ax=0; // AZAZAZAZ for(int k=0;k<=25;k++)zzq[k]=pos[k]; int dis=pos[j]; for(int k=0;k<=25;k++) while(pos[k]<=dis)pos[k]=nx[pos[k]]; l[j]--; for(int k=0;k<=25;k++){ int num=cnt[pos[k]]; // if(pos[k]==i&&k!=j)num--; if(num<l[k])ax=1; // if(l[k]>m-i&&k!=j)ax=1; } int q=0; for(int pp=0;pp<=25;pp++)if(l[pp]>0)q+=l[pp]; //cout<<q<<endl; if(q>m-i)ax=1; if(ax){ for(int k=0;k<=25;k++) pos[k]=zzq[k]; l[j]++; continue;} //AFAEFAEEFD az[j]++; st[i-1]='a'+j; //cout<<pos[j]<<endl; break; } //cout<<zl<<endl; //if(!zl){break;cout<<m<<' ';} if(st[i-1]=='0')zl=1; } if(zl){cout<<-1<<endl;continue;} for(int i=0;i<m;i++)cout<<st[i]; cout<<endl; } return 0; }
1001
考虑dp
https://www.cnblogs.com/DeaphetS/p/11229389.html
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
#include<bits/stdc++.h> using namespace std; #define ll long long const int mo=998244353; ll dp[102][102][102][2],n,m,ans; vector<int>r[102],x[102]; int main(){ int t; //freopen("p.in","r",stdin); //freopen("p.out","w",stdout); cin>>t; while(t){ t--; cin>>n>>m; memset(dp,0,sizeof(dp)); for(int i=1;i<=n;i++){ r[i].clear(); x[i].clear(); } for(int i=1;i<=m;i++){ int a,b,c; cin>>a>>b>>c; r[b].push_back(a); x[b].push_back(c); } dp[0][0][0][0]=1; for(int cur=1;cur<=n;cur++){ int o=cur%2; for(int i=0;i<=cur;i++) for(int j=i;j<=cur;j++) for(int k=j;k<=cur;k++) dp[i][j][k][o]=0; for(int i=0;i<=cur;i++) for(int j=i;j<=cur;j++) for(int k=j;k<=cur;k++) { dp[i][j][cur-1][o]=(dp[i][j][cur-1][o]+dp[i][j][k][o^1])%mo; dp[i][k][cur-1][o]=(dp[i][k][cur-1][o]+dp[i][j][k][o^1])%mo; dp[j][k][cur-1][o]=(dp[j][k][cur-1][o]+dp[i][j][k][o^1])%mo; dp[i][j][k][o]=(dp[i][j][k][o]+dp[i][j][k][o^1])%mo;} for(int i=0;i<=cur;i++) for(int j=i;j<=cur;j++) for(int k=j;k<=cur;k++) for(int az=0;az<r[cur].size();az++){ int ql=r[cur][az],qx=x[cur][az]; if((i>=ql)+(j>=ql)+(k>=ql)+(cur>=ql)!=qx) dp[i][j][k][o]=0; } } ans=0; for(int i=0;i<=n;i++) for(int j=i;j<=n;j++) for(int k=j;k<=n;k++) ans=(ans+dp[i][j][k][n%2])%mo; cout<<ans<<endl; } return 0; }
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