#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define maxn 1000010
using namespace std;
int n,a[maxn],cnt1,cnt2;
int qread(){int i=0;char ch=getchar();while(ch<'0'||ch>'9')ch=getchar();while(ch<='9'&&ch>='0'){i=i*10+ch-'0';ch=getchar();}return i;
}
int main(){freopen("book.in","r",stdin);freopen("book.out","w",stdout);
//    freopen("Cola.txt","r",stdin);scanf("%d",&n);for(int i=1;i<=n;i++)a[i]=qread();for(int i=1;i<=n;i++){if(a[i]==5)cnt1++;if(a[i]==10){if(cnt1==0){puts("NO");return 0;}else {cnt2++;cnt1--;}}if(a[i]==20){if(cnt1==0||(cnt2==0&&cnt1<3)){puts("NO");return 0;}if(cnt2){cnt2--;cnt1--;}else{cnt1-=3;}}}puts("YES");return 0;
}

#include<iostream>
#include<cstdio>
#include<cstring>
#define maxn 1000010
using namespace std;
int n,a[maxn],s1[maxn],s2[maxn],top1,top2,m,sid1[maxn],sid2[maxn],b[maxn];
bool ex[maxn];
void out(){for(int i=1;i<=n;i++){if(b[i]==1)printf("+%d ",a[i]);else printf("-%d ",a[i]);}
}
int main(){freopen("program.in","r",stdin);freopen("program.out","w",stdout);
//    freopen("Cola.txt","r",stdin);scanf("%d",&n);for(int i=1;i<=n;i++)scanf("%d",&a[i]);scanf("%d",&m);int x;for(int i=1;i<=m;i++){scanf("%d",&x);ex[x]=1;}for(int i=1;i<=n;i++){if(ex[i]){top2+=1;s2[top2]=a[i];b[i]=-1;sid2[top2]=i;while(top2){if(s2[top2]==s1[top1]){b[sid2[top2]]=-1;b[sid1[top1]]=1;top1-=1;top2-=1;}else{sid2[top2+1]=sid1[top1];top2+=1;s2[top2]=s1[top1];top1-=1;}if(top1<0){puts("NO");return 0;}}}else{top1+=1;s1[top1]=a[i];sid1[top1]=i;}}if(top1==0&&top2==0){out();return 0;}while(top1){s2[++top2]=s1[top1];sid2[top2]=sid1[top1];top1--;while(top2){if(s2[top2]==s1[top1]){b[sid2[top2]]=-1;b[sid1[top1]]=1;top1--;top2--;}else{sid2[top2+1]=sid1[top1];s2[++top2]=s1[top1--];}if(top1<0){puts("NO");return 0;}}}out();return 0;
}

#include<iostream>
#include<cstdio>
#include<vector>
#define maxn 110
using namespace std;
int n,m,num,head[maxn],q,s,t,st[maxn],top;
struct node{int to,pre,v;
}e[maxn*maxn*5];
void Insert(int from,int to,int v){e[++num].to=to;e[num].v=v;e[num].pre=head[from];head[from]=num;
}
bool vis[maxn],flag;
void dfs(int now){if(now==t&&top==0){flag=1;return;}if(flag)return;vector<int>zu;for(int i=1;i<=top;i++)zu.push_back(st[i]);for(int i=head[now];i;i=e[i].pre){int to=e[i].to;if(vis[to])continue;else{vis[to]=1;if(e[i].v==0){dfs(to);top=0;for(int j=0;j<zu.size();j++)st[++top]=zu[j];vis[to]=0;continue;}for(int j=1;j<=10;j+=2){if(e[i].v>0){for(int k=1;k<=j;k++){top=top+1;st[top]=e[i].v;}dfs(to);if(flag)return;top=0;for(int k=0;k<zu.size();k++)top=top+1,st[top]=zu[k];}if(e[i].v<0){top-=j-1;if(st[top]!=-e[i].v||top<1)break;else top-=1;dfs(to);top=0;for(int k=0;k<zu.size();k++)st[++top]=zu[k];}}vis[to]=0;}}
}
int main(){freopen("maze.in","r",stdin);freopen("maze.out","w",stdout);
//    freopen("Cola.txt","r",stdin);scanf("%d%d",&n,&m);int x,y,z;for(int i=1;i<=m;i++){scanf("%d%d%d",&x,&y,&z);Insert(x,y,z);Insert(y,x,z);}scanf("%d",&q);while(q--){flag=0;top=0;scanf("%d%d",&s,&t);vis[s]=1;dfs(s);vis[s]=1;if(flag)puts("YES");else puts("NO");}return 0;
}

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cstdlib>
using namespace std;
int n,m,g[105][105][40],q[105*105*40][3],t,x,y,z;
int main(){
//    freopen("maze.in","r",stdin);freopen("maze.out","w",stdout);freopen("maze20.in","r",stdin);scanf("%d%d",&n,&m);for(int i=1;i<=m;i++){scanf("%d%d%d",&x,&y,&z);if(z!=0){if(z<0)z=abs(z);else z+=10;g[x][y][z]=1;g[y][x][z]=1;}else{g[x][y][z]=1;g[y][x][z]=1;t++;q[t][0]=x;q[t][1]=y;q[t][2]=0;t++;q[t][0]=y;q[t][1]=x;q[t][2]=0;}}for(int i=1;i<=n;i++){g[i][i][0]=1;t++;q[t][0]=i;q[t][1]=i;q[t][2]=0;}for(int s=1;s<=t;s++){int x=q[s][0],y=q[s][1],sta=q[s][2];if(sta!=0){for(int i=1;i<=n;i++){if(g[i][x][sta-10]==1){if(g[i][y][0]==0){g[i][y][0]=1;t++;q[t][0]=i;q[t][1]=y;q[t][2]=0;}}}}else{for(int i=1;i<=n;i++){if(g[i][x][0]==1&&g[i][y][0]==0){g[i][y][0]=1;t++;q[t][0]=i;q[t][1]=y;q[t][2]=0;}if(g[y][i][0]==1&&g[x][i][0]==0){g[x][i][0]=1;t++;q[t][0]=x;q[t][1]=i;q[t][2]=0;}for(int j=1;j<=10;j++){if(g[y][i][j]==1&&g[x][i][j+20]==0){g[x][i][j+20]=1;t++;q[t][0]=x;q[t][1]=i;q[t][2]=j+20;}}}}}int tt=0;scanf("%d",&tt);for(;tt;tt--){scanf("%d%d",&x,&y);if(g[x][y][0]==1)puts("YES");else puts("NO");}
}

预计得分100+80+0
实际得分100+100+5
T1较简单，是以前做过的原题。T2看到函数递归就觉得应该和栈有关系，仔细研究，这不就是个括号序列吗，一开始以为要用双向链表，后来发现加个数组记录一下id，再加一个栈模拟退栈就好了，虽然和标解不太一样，但是A了。T3我思索良久，想过建分层图，但复杂度太高，正确性也很玄学，所以就写了个dfs，才搜了5分
今天的题都是关于栈的，发挥的还好，但我觉得T3的dfs应该再优化一下，尽量拿到更多部分分