[ZJOI2006]三色二叉树

[ZJOI2006]三色二叉树

BZOJ
luogu
分3种颜色讨论转移一下

#include<bits/stdc++.h>
using namespace std;
const int _=500005;
int n,now;
int ls[_],rs[_],r[_],g[_],b[_];
char s[_];
void bu(int u){
    if(s[u]=='1'||s[u]=='2'){++now;bu(ls[u]=now);}
    if(s[u]=='2'){++now;bu(rs[u]=now);}
}
void qmax(int u){
    if(s[u]=='0'){g[u]=1;r[u]=0;b[u]=0;return;}
    if(s[u]=='1'){
        int v=ls[u];qmax(v);
        g[u]=max(b[v],r[v])+1;
        r[u]=max(g[v],b[v]);
        b[u]=max(g[v],r[v]);
    }
    if(s[u]=='2'){
        qmax(ls[u]);qmax(rs[u]);
        g[u]=max(b[ls[u]]+r[rs[u]],r[ls[u]]+b[rs[u]])+1;
        b[u]=max(g[ls[u]]+r[rs[u]],r[ls[u]]+g[rs[u]]);
        r[u]=max(b[ls[u]]+g[rs[u]],g[ls[u]]+b[rs[u]]);
    }
}
void qmin(int u){
    if(s[u]=='0'){g[u]=1;r[u]=0;b[u]=0;return;}
    if(s[u]=='1'){
        int v=ls[u];qmin(v);
        g[u]=min(b[v],r[v])+1;
        r[u]=min(g[v],b[v]);
        b[u]=min(g[v],r[v]);
    }
    if(s[u]=='2'){
        qmin(ls[u]);qmin(rs[u]);
        g[u]=min(b[ls[u]]+r[rs[u]],r[ls[u]]+b[rs[u]])+1;
        b[u]=min(g[ls[u]]+r[rs[u]],r[ls[u]]+g[rs[u]]);
        r[u]=min(b[ls[u]]+g[rs[u]],g[ls[u]]+b[rs[u]]);
    }
}
int main(){
    scanf("%s",s+1);n=strlen(s+1);
    bu(now=1);
    qmax(1);
    printf("%d ",max(g[1],max(r[1],b[1])));
    memset(g,63,sizeof(g));
    memset(r,63,sizeof(r));
    memset(b,63,sizeof(b));
    qmin(1);
    printf("%d\n",min(g[1],min(b[1],r[1])));
    return 0;
}