Codeforces - 71E 状压DP

参考官方题解

#include<bits/stdc++.h>
#define rep(i,j,k) for(register int i=j;i<=k;i++)
#define rrep(i,j,k) for(register int i=j;i>=k;i--)
using namespace std;
string s[100]={"H","He","Li","Be","B",
"C","N","O","F","Ne",
"Na","Mg","Al","Si","P",
"S","Cl","Ar","K","Ca",
"Sc","Ti","V","Cr","Mn","Fe","Co","Ni","Cu","Zn","Ga","Ge","As","Se","Br","Kr",
"Rb","Sr","Y","Zr","Nb","Mo","Tc","Ru","Rh","Pd","Ag","Cd","In","Sn","Sb","Te","I","Xe","Cs","Ba","La",
"Ce","Pr","Nd","Pm","Sm","Eu","Gd","Tb","Dy","Ho","Er","Tm","Yb","Lu","Hf","Ta","W","Re","Os","Ir","Pt","Au","Hg","Tl",
"Pb","Bi","Po","At","Rn","Fr","Ra","Ac","Th","Pa","U","Np","Pu","Am","Cm","Bk","Cf","Es","Fm"};
int num[111],ans[111][111],vec[111],que[111],p[1<<18|1];
int dp1[1<<18|1],dp2[1<<18|1];
int n,k,sum1,sum2;
string str;
bool go(){
    memset(dp1,0,sizeof dp1);
    memset(dp2,0,sizeof dp2);
//  memset(dp2,-1,sizeof dp2);
    rep(S,1,(1<<n)-1){
        rep(i,1,n){
            if((S>>(i-1))&1){
                dp1[S]+=vec[i];
            }
        }
    }
    rep(S,1,(1<<n)-1){
        dp2[S]=-1;
        for(int S0=S;S0;S0=(S0-1)&S){
            if(dp2[S^S0]!=-1&&que[dp2[S^S0]+1]==dp1[S0]){
                dp2[S]=dp2[S^S0]+1;
                p[S]=S^S0;
            }
        }
    }
    if(dp2[(1<<n)-1]!=k) return 0;
    int x=(1<<n)-1;
    rrep(i,k,1){
        rep(j,1,n){
            if(1<<(j-1)&(x^p[x])){
                ans[i][++num[i]]=j;
            }
        }
        x=p[x];
    }
    return 1;
}
inline void print(){
    cout<<"YES"<<endl;
    rep(i,1,k){
        cout<<s[vec[ans[i][1]]-1];
        rep(j,2,num[i]){
            cout<<"+"<<s[vec[ans[i][j]]-1];
        }
        cout<<"->"<<s[que[i]-1]<<endl;
    }
}
int main(){
    while(cin>>n>>k){
        sum1=sum2=0;
        memset(num,0,sizeof num);
        rep(i,1,n){
            cin>>str;
            rep(j,0,100-1){
                if(str==s[j]){
                    vec[i]=j+1;
                    sum1+=j+1;
                    break;
                }
            }
        }
        rep(i,1,k){
            cin>>str;
            rep(j,0,100-1){
                if(str==s[j]){
                    que[i]=j+1;
                    sum2+=j+1;
                    break;
                }
            }
        }
        if(sum1==sum2&&go()) print();
        else cout<<"NO"<<endl;
    }
    return 0;
}

原文地址：https://www.cnblogs.com/caturra/p/8456545.html