HYSBZ 2243 染色 LCT学习

这道题感觉非常简单，（其实用树链剖分写的话肯定快多了），一个区间染色问题，需要记录一下最左段，最右端的颜色，还有就是有几段，这样才能维护起来，在一个傻逼地方wa了好多遍，翻转的时候，左端的颜色变成了右端的颜色，右端的颜色变成了左端的颜色。下面是代码：

#include <cstring>
#include <cmath>
#include <algorithm>
#include <cstdio>
#include <vector>
#define LL long long
#define INF 0x3fffffff
#define FOR(i,x,y)  for(int i = x;i < y;i ++)
#define IFOR(i,x,y) for(int i = x;i > y;i --)
#define MAXN 110000

using namespace std;

int n,m;
vector <int> mat[MAXN];

struct LCT{
    int pre[MAXN],ch[MAXN][2],key[MAXN],flip[MAXN];
    int ans[MAXN],l[MAXN],r[MAXN],lazy[MAXN];
    bool rt[MAXN];

    void Update_Lazy(int x,int w){
        if(!x)  return;
        lazy[x] = w;
        key[x] = w;
        l[x] = w;
        r[x] = w;
        ans[x] = 1;
    }

    void Update_Flip(int x){
        if(!x)  return;
        swap(l[x],r[x]);
        swap(ch[x][0],ch[x][1]);
        flip[x] ^= 1;
    }

    void Init(){
        memset(ch,0,sizeof(ch));
        memset(flip,0,sizeof(flip));
        memset(rt,true,sizeof(rt));
        FOR(i,1,n+1){
            l[i] = r[i] = key[i];
            ans[i] = 1;
            lazy[i] = -1;
        }
    }

    void PushUp(int x){
        ans[x] = 1; l[x] = r[x] = key[x];
        if(ch[x][0]){
            ans[x] += ans[ch[x][0]];
            if(r[ch[x][0]] == key[x])   ans[x] --;
            l[x] = l[ch[x][0]];
        }
        if(ch[x][1]){
            ans[x] += ans[ch[x][1]];
            if(l[ch[x][1]] == key[x])   ans[x] --;
            r[x] = r[ch[x][1]];
        }
    }

    void PushDown(int x){
        if(lazy[x] != -1){
            Update_Lazy(ch[x][0],lazy[x]);
            Update_Lazy(ch[x][1],lazy[x]);
            lazy[x] = -1;
        }
        if(flip[x]){
            Update_Flip(ch[x][0]);
            Update_Flip(ch[x][1]);
            flip[x] = 0;
        }
    }

    void Rotate(int x,int kind){
        int y = pre[x];
        PushDown(y);
        PushDown(x);
        ch[y][!kind] = ch[x][kind];
        if(ch[x][kind]) pre[ch[x][kind]] = y;
        if(rt[y]){
            rt[x] = true;
            rt[y] = false;
        }
        else{
            if(ch[pre[y]][1] == y)  ch[pre[y]][1] = x;
            if(ch[pre[y]][0] == y)  ch[pre[y]][0] = x;
        }
        pre[x] = pre[y];
        pre[y] = x;
        ch[x][kind] = y;
        PushUp(y);
    }

    void Splay(int x){
        PushDown(x);
        while(!rt[x]){
            int y = pre[x];
            int z = pre[y];
            if(rt[y]){
                PushDown(y); PushDown(x);
                Rotate(x,ch[y][0] == x);
            }
            else{
                PushDown(z); PushDown(y); PushDown(x);
                int kind = ch[z][0] == y;
                if(ch[y][kind] == x){
                    Rotate(x,!kind);
                    Rotate(x,kind);
                }
                else{
                    Rotate(y,kind);
                    Rotate(x,kind);
                }
            }
        }
        PushUp(x);
    }

    void Access(int x){
        int fa = 0;
        for(;x;x = pre[fa = x]){
            Splay(x);
            rt[ch[x][1]] = true;
            rt[ch[x][1] = fa] = false;
            PushUp(x);
        }
    }

    int GetRoot(int x){
        Access(x);
        Splay(x);
        while(ch[x][0]) x = ch[x][0];
        return x;
    }

    void MakeRoot(int x){
        Access(x);
        Splay(x);
        Update_Flip(x);
    }

    void Modify(int u,int v,int w){
        MakeRoot(u);
        Access(v);
        Splay(v);
        Update_Lazy(v,w);
    }

    int Query(int u,int v){
        MakeRoot(u);
        Access(v);
        Splay(v);
        return ans[v];
    }

}lct;

void dfs(int u,int fa){
    lct.pre[u] = fa;
    for(int i = 0;i < mat[u].size();i ++){
        int v = mat[u][i];
        if(v == fa) continue;
        dfs(v,u);
    }
}

int main(){
    //freopen("test.in","r",stdin);
    while(~scanf("%d%d",&n,&m)){
        FOR(i,1,n+1)    mat[i].clear();
        FOR(i,1,n+1)    scanf("%d",&lct.key[i]);
        FOR(i,1,n){
            int u,v;
            scanf("%d%d",&u,&v);
            mat[u].push_back(v);
            mat[v].push_back(u);
        }
        dfs(1,0);
        lct.Init();
        char op[10];
        FOR(i,0,m){
            scanf("%s",op);
            if(op[0] == 'Q'){
                int u,v;
                scanf("%d%d",&u,&v);
                printf("%d\n",lct.Query(u,v));
            }
            else{
                int u,v,w;
                scanf("%d%d%d",&u,&v,&w);
                lct.Modify(u,v,w);
            }
        }
    }
    return 0;
}

版权声明：本文为博主原创文章，未经博主允许不得转载。