BZOJ1493 NOI2007 项链工厂 线段树模拟

提交地址：http://www.lydsy.com/JudgeOnline/problem.php?id=1493

题目大意：给一个数列，进行一系列操作。包括旋转，翻转，改变等操作，以及查询颜色段数。

题目分析：数列中元素的相对位置没有改变，因此不需要用splay去做，而是可以用线段树解决这类问题。

旋转操作直接改变变量rotate，翻转操作用异或即可。每次询问先利用rotate求出当前1号位是谁，这样可以根据翻转标记确定区间。如果区间跨越n，那么合并的时候要考虑左边一段的右端和右边一段的左端。相同的时候答案要减少1.

对于swap操作，由于是单点的，可以暴力在树上做。

这题以我的代码水平来说比较难打。

代码如下：

 #include<iostream>
 #include<cstdio>
 #include<cstdlib>
 #include<cstring>
 #include<algorithm>
 using namespace std;

 const int maxn = ;
 struct node{
     int lazy;
     int lft,rgt,tot,full;
 }t[maxn<<];
 int n,c;
 int x[maxn];
 int fz,rt; // fanzhuan rotate
 int tl,tr;

 void push_down(int now){
     t[now<<].lazy = t[now<<|].lazy = t[now].lazy;
     t[now].lft = t[now].rgt = t[now].lazy; t[now].tot = ;
     t[now].lazy = ;t[now].full = ;
 }

 void push_up(int now){
     int L=(now<<),R = L+;
     if(t[now].lazy)push_down(now);
     if(t[L].lazy)push_down(L); if(t[R].lazy) push_down(R);
     t[now].lft = t[L].lft; t[now].rgt = t[R].rgt;
     t[now].tot = t[L].tot + t[R].tot;
     if(t[L].rgt == t[R].lft) t[now].tot--;
     if(t[L].full && t[R].full && t[L].rgt == t[R].rgt) t[now].full=;
     else t[now].full = ;
 }

 void build_tree(int l,int r,int now){
     if(l == r){
     t[now].lazy = ; t[now].lft = x[l]; t[now].rgt = x[l];
     t[now].tot = ;t[now].full = ;
     }else{
     int mid = (l+r>>);int L=(now<<),R = L+;
     build_tree(l,mid,L); build_tree(mid+,r,R);
     push_up(now);
     }
 }

 void read(){
     scanf("%d%d",&n,&c);
     for(int i=;i<=n;i++){
     scanf("%d",&x[i]);
     }
     build_tree(,n,);
 }

 void Rotate(){
     int now; scanf("%d",&now);
     if(fz == ) rt += (n-now);
     else rt += now;
     rt %= n;
 }

 int get_ans(int l,int r,int now){
     if(now == ) tl = ,tr = n;
     if(t[now].lazy) push_down(now);
     if(tl > r || tr < l) return ;
     if(tl >= l && tr <= r) return t[now].tot;
     int mid = (tl+tr) / ;
     int ans = ;
     int tmp = tr; tr=mid;
     int nnow = get_ans(l,r,now<<);
     ans += nnow;
     tr = tmp;tmp = tl; tl = mid+;
     int know = get_ans(l,r,now<<|);
     ans += know;
     tl = tmp;
     if(tr-tl!=&&t[now<<].rgt == t[now<<|].lft&&nnow&&know) ans--;
     push_up(now);
     return ans;
 }

 int get_color(int ord,int now){
     if(now == ) tl = ,tr = n;
     if(t[now].lazy) {push_down(now);return t[now].lft;}
     if(tl == tr) return t[now].lft;
     int mid = (tl+tr)/;
     int ans;
     if(mid >= ord){tr = mid; ans = get_color(ord,now<<);}
     else {tl = mid+; ans = get_color(ord,now<<|);}
     push_up(now);
     return ans;
 }

 void Tpaint(int l,int r,int now,int xc){
     if(now == ) tl = ,tr = n;
     if(t[now].lazy) {push_down(now);}
     if(tl > r || tr < l) return;
     if(tl >= l && tr <= r) {t[now].lazy = xc;push_down(now);return;}
     int mid = (tl+tr)/;
     int tmp = tr;tr = mid;
     Tpaint(l,r,now<<,xc);
     tr = tmp; tmp = tl; tl = mid+;
     Tpaint(l,r,now<<|,xc);
     tl = tmp;
     push_up(now);
 }

 int cnt;
 void Count(){
     int l,r,flag=,flag2=;
     char ch = getchar();
     cnt++;
     if(ch != 'S') {
     l = ,r=n;
     int ans = t[].tot-(t[].lft == t[].rgt && t[].full==);
     printf("%d\n",ans);
     return;
     }else {
     scanf("%d%d",&l,&r);
     }
     int st = (-rt); if(st <= ) st += n;
     if(fz == ){
     l = st-l+; r = st-r+;
     if(l <= ) l += n; if(r <= ) r += n;
     int ans = ;
     if(l < r){
         ans += get_ans(,l,);
         ans += get_ans(r,n,);
         if(t[].lft == t[].rgt) ans--;
     }else ans += get_ans(r,l,);
     printf("%d\n",ans);
     }else{
     l = st+l-; r = st+r-;
     if(l > n) l -= n; if(r > n) r -= n;
     int ans = ;
     if(l > r){
         ans += get_ans(,r,);
         ans += get_ans(l,n,);
         if(t[].lft == t[].rgt) ans--;
     }else ans += get_ans(l,r,);
     printf("%d\n",ans);
     }
 }

 void Paint(){
     int l,r,xc; scanf("%d%d%d",&l,&r,&xc);
     int st = (-rt); if(st <= ) st += n;
     if(fz == ){
     l = st-l+; r = st-r+;
     if(l <= ) l += n; if(r <= ) r += n;
     if(l < r){ Tpaint(,l,,xc); Tpaint(r,n,,xc);}
     else Tpaint(r,l,,xc);
     }else{
     l = st+l-; r = st+r-;
     if(l > n) l -= n; if(r > n) r -= n;
     if(l > r){ Tpaint(,r,,xc); Tpaint(l,n,,xc);}
     else Tpaint(l,r,,xc);
     }
 }

 void Swap(){
     int l,r; scanf("%d%d",&l,&r);
     int st = (-rt); if(st <= ) st += n;
     if(fz == ){
     l = st-l+; r = st-r+;
     if(l <= ) l += n; if(r <= ) r+= n;
     }else{
     l = st+l-; r = st+r-;
     if(l > n) l -= n; if(r > n) r -= n;
     }
     int nowl = get_color(l,),nowr = get_color(r,);
     Tpaint(l,l,,nowr); Tpaint(r,r,,nowl);
 }

 void work(){
     int q; scanf("%d",&q);
     for(int i=;i<=q;i++){
     char ch = getchar();
     while(ch > 'Z' || ch < 'A')ch = getchar();
     switch(ch){
     case 'R':{Rotate();break;}
     case 'F':{fz ^= ;break;}
     case 'S':{Swap();break;}
     case 'P':{Paint();break;}
     case 'C':{Count();break;}
     }
     }
 }

 int main(){
     //freopen("1.in","r",stdin);
     //freopen("1.out","w",stdout);
     read();
     work();
     return ;
 }