165. 小猫爬山 - AcWing题库(dfs)

#include<iostream>
#include<string>
#include<bitset> 
#include<cstring>
#include<algorithm>
using namespace std;
const int N=18;
bool vis[N];
int a[N],n,ans,sum[N],k;
bool cmp(int x,int y){return x>y;
}
void dfs(int x,int t){if(t>=ans)return;if(x==n){ans=min(ans,t);return;}for(int i=1;i<=t;i++){//第一种选择--放到原数组if(sum[i]+a[x]<=k){sum[i]+=a[x];dfs(x+1,t);sum[i]-=a[x];}}sum[t+1]=a[x];//第二种选择放到新数组中dfs(x+1,t+1);sum[t+1]=0;
}
int main(){cin>>n>>k;for(int i=0;i<n;i++){cin>>a[i];}sort(a,a+n,cmp);ans=n;dfs(0,1);cout<<ans<<endl;
}

167. 木棒 - AcWing题库(dfs+剪枝--重点理解)

#include<iostream>
#include<string>
#include<bitset> 
#include<cstring>
#include<algorithm>
using namespace std;
int n;
int a[65];
int length,sum;
bool vis[65];
bool cmp(int x,int y){return x>y;
}
int dfs(int u,int h,int x){//u为几组木棍成功， h目前长度 ,x为枚举位置if(u*length==sum)return 1;//总长度相等就成功if(h==length)return dfs(u+1,0,0);//这组成功for(int i=x;i<n;i++){if(h+a[i]>length||vis[i])continue;vis[i]=true;//标记使用if(dfs(u,h+a[i],i+1)==1)return 1;vis[i]=false;//取消标记if(!h||a[i]+h==length)return false;//第一根失败，或最后一根失败直接失败int j=i;//长度相等的一定失败while(j<n&&a[j]==a[i])j++;i=j-1;}return false;
}
int main(){while(cin>>n&&n){memset(vis,0,sizeof(vis));sum=0;for(int i=0;i<n;i++){cin>>a[i];sum+=a[i];}sort(a,a+n,cmp);length=1;for(length=1;length<=sum;length++){if(sum%length==0&&dfs(0,0,0)){cout<<length<<endl;break;}}}
}

4974. 最长连续子序列 - AcWing题库(双指针)

#include<iostream>
#include<queue>
#include<map>
using namespace std;
map<int,int>ma;
typedef pair<int,int>PII;
int a[1000005];
int p[1000005];
int main(){int n;cin>>n;for(int i=0;i<n;i++){cin>>a[i];}ma[a[0]]++;int s=1;int ans=0;for(int i=0,j=0;j<n;){if(s<=2){ans=max(ans,j-i+1);j++;if(ma[a[j]]==0)s++;ma[a[j]]++;}else {ma[a[i]]--;if(ma[a[i]]==0)s--;i++;}}cout<<ans<<endl;
}

3321. ATM队列 - AcWing题库(排序--签到)

#include<iostream>
#include<queue>
#include<map>
#include<algorithm>
using namespace std;
map<int,int>ma;
typedef pair<int,int>PII;
struct node{int x,y;
}a[1000005];
bool cmp(node q,node w){if(q.x!=w.x)return q.x<w.x;return q.y<w.y;
}
int main(){int t;cin>>t;for(int i=1;i<=t;i++){int n,k;cin>>n>>k;for(int j=0;j<n;j++){int q;cin>>q;a[j].x=q/k;if(q%k!=0)a[j].x++;a[j].y=j+1;}printf("Case #%d: ",i);sort(a,a+n,cmp);for(int j=0;j<n;j++){cout<<a[j].y<<' ';}cout<<endl;}
}