UVA - 10317 Equating Equations(普通的暴力枚举 dfs枚举 c（n,m）)

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#include <cstdio>#include <iostream>#include <cstring>#include <algorithm>#include <cmath>#include <vector>#include <map>#include <cctype>using namespace std;typedef long long LL;char str[100000];vector<char> Punct;vector<int>  dig;int m ;void solve(){  Punct.clear();  dig.clear();  int n=strlen(str);  int ln=0,rn=0,now_position=0;  for(int i=0;i<n;i++){    if(str[i]!=' '){      int is_negative=0;      if(ispunct(str[i])){        if(str[i+1]!=' '){          is_negative=1;        }        else{            Punct.push_back(str[i]);            if(Punct.back()=='=')                now_position = 1;            continue;        }      }      int j,num=0;      for(j=i;j<n;j++){        if(str[j]==' ') break;        if(isdigit(str[j]))          num=num*10+str[j]-'0';      }      if(is_negative) num=-num;      if(!now_position){        if(Punct.empty()||Punct.back()=='+'){            ln++;        } else rn++;      }      else {        if(Punct.empty()||Punct.back()=='+'||Punct.back()=='='){            rn++;        } else ln++;      }      dig.push_back(num);      i=j;    }  }  m = ln; // cout<<Punct.size()<<endl;}int SUM = 0;int vis[100];vector<int> ans1,ans2;void print(){   int now_position = 0,last=1;        for(int i=0;i<dig.size();i++){          if(vis[i]) ans1.push_back(dig[i]);          else ans2.push_back(dig[i]);        }        int s1=0,s2=0,p=0;        for(int i=0;i<dig.size();i++){          if(i) printf(" ");          if(!now_position){            if(last){                printf("%d",ans1[s1++]);            }            else printf("%d",ans2[s2++]);          }          else {            if(last){                printf("%d",ans2[s2++]);            }            else printf("%d",ans1[s1++]);          }          if(i!=dig.size()-1){          printf(" %c",Punct[p]);          if(Punct[p]=='='){ now_position = 1; last=1;}          else if(Punct[p]=='+') last=1;          else last=0;          p++;          }        }        printf("\n");}bool fff = false;void dfs(int i,int depth,int num){  if(fff) return ;  if(depth == m){      if(num==SUM){         print(); fff= true;      }      return ;  }  for(int j=i+1;j<dig.size()&&j+m-depth-1<dig.size();j++){     vis[j] = 1;     dfs(j,depth+1,num+dig[j]);     vis[j] = 0;  }}int main(){    while(gets(str)!=NULL){      solve();      SUM = 0;      for(int i=0;i<dig.size();i++){        SUM+=dig[i];      }      if(abs(SUM)%2 != 0){          printf("no solution\n");          continue;      }      ans1.clear(); ans2.clear();      fff = false;      SUM/=2;      memset(vis,0,sizeof(vis));      dfs(-1,0,0);      if(!fff){        printf("no solution\n");      }    }    return 0;}
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