hdu 4046 2011北京赛区网络赛G 线段树 ***

还带这么做的，卧槽，15分钟就被A了的题，居然没搞出来

若某位是1，则前两个为wb，这位就是w

 #include<cstdio>
 #include<cstring>
 #define lson l,m,rt<<1
 #define rson m+1,r,rt<<1|1
 using namespace std;
 const int maxn=;
 int n,m,sum[maxn<<];
 char str[maxn];
 int num[maxn];
 void pushup(int rt)
 {
     sum[rt]=sum[rt<<]+sum[rt<<|];
 }
 void build(int l,int r,int rt)
 {
     if(l==r)
     {
         sum[rt]=num[l];
         return;
     }
     int m=(l+r)>>;
     build(lson);
     build(rson);
     pushup(rt);
 }
 int query(int L,int R,int l,int r,int rt)
 {
     if(L<=l&&r<=R)
     {
         return sum[rt];
     }
     int m=(l+r)>>;
     int ans=;
     if(L<=m) ans+=query(L,R,lson);
     if(R>m)  ans+=query(L,R,rson);
     return ans;
 }
 void update(int p,int val,int l,int r,int rt)
 {
     if(l==r)
     {
         sum[rt]=val;
         return;
     }
     int m=(l+r)>>;
     if(p<=m) update(p,val,lson);
     else      update(p,val,rson);
     pushup(rt);
 }
 int main()
 {
     int t,T;
     scanf("%d",&T);
     for(int t=;t<=T;t++)
     {
         printf("Case %d:\n",t);
         scanf("%d%d%s",&n,&m,str+);
         memset(num,,sizeof(num));
         for(int i=;i<=n;i++)
             if(str[i-]=='w'&&str[i-]=='b'&&str[i]=='w')  num[i]=;
         build(,n,);
         int k,a,b;
         char ch[];
         while (m--)
         {
             scanf("%d",&k);
             if(k==)
             {
                 scanf("%d%d",&a,&b);
                 a++;b++;   //字符串从1开始，所以下标都加1
                 if(b-a<)  printf("0\n");
                 else       printf("%d\n",query(a+,b,,n,));
             }
             else
             {
                 scanf("%d%s",&a,ch);
                 a++;
                 if(ch[]==str[a]) continue;//修改的和以前一样，这不用任何操作
                 if(a>=)
                 {
                     if(str[a-]=='w'&&str[a-]=='b'&&str[a]=='w')
                         update(a,,,n,);
                     if(str[a-]=='w'&&str[a-]=='b'&&str[a]=='b')
                         update(a,,,n,);
                 }
                 if(a>=&&a+<=n)
                 {
                     if(str[a-]=='w'&&str[a]=='b'&&str[a+]=='w')
                         update(a+,,,n,);
                     if(str[a-]=='w'&&str[a]=='w'&&str[a+]=='w')
                         update(a+,,,n,);
                 }
                 if(a+<=n)
                 {
                     if(str[a]=='w'&&str[a+]=='b'&&str[a+]=='w')
                         update(a+,,,n,);
                     if(str[a]=='b'&&str[a+]=='b'&&str[a+]=='w')
                         update(a+,,,n,);
                 }
                 str[a]=ch[];
             }
         }
     }
     return ;
 }

 #include<cstdio>
 #include<iostream>
 #include<algorithm>
 #include<cstring>
 #include<cmath>
 #include<queue>
 #define lson l,mid,rt<<1
 #define rson mid+1,r,rt<<1|1
 #define root 1,n,1
 #define mid ((l+r)>>1)
 #define ll long long
 #define cl(a) memset(a,0,sizeof(a))
 #define ts printf("*****\n");
 using namespace std;
 const int MAXN=;
 int sum[MAXN<<],lsum[MAXN<<],rsum[MAXN<<],lc[MAXN<<],rc[MAXN<<];
 int n,m,tt;
 char s[MAXN];
 void pushup(int l,int r,int rt)
 {
     //printf("%d %d %d %d\n",l,r,rt,mid);
     /*if(mid==3)
     {
         printf("%s\n",s+1);
         printf("%c %c %c\n",s[mid-1],s[mid],s[mid+1]);
     }*/
     sum[rt]=sum[rt<<]+sum[rt<<|];
     if(/*(s[mid]=='b'&&s[mid-1]=='w'&&s[mid+1]=='w')||*/(s[mid]=='w'&&s[mid+]=='b'&&s[mid+]=='w')&&mid+<=n)
     {
         sum[rt]+=;
     }
 }
 void build(int l,int r,int rt)
 {
     if(l==r)
     {
         sum[rt]=;
         return;
     }
     build(lson);
     build(rson);
     pushup(l,r,rt);
 }
 void update(int pos,int val,int l,int r,int rt)
 {
     if(l==r)
     {
         return;
     }
     update(pos,val,lson);
     update(pos,val,rson);
     pushup(l,r,rt);
 }
 int query(int L,int R,int l,int r,int rt)
 {

     //printf("%d %d %d %d %d\n",L,R,l,r,rt);
     if(L<=l&&r<=R)
     {
         return sum[rt];
     }
     if(R<=mid) return query(L,R,lson);
     if(L>mid) return query(L,R,rson);

     int ta,tb;
     ta=query(L,R,lson);
     tb=query(L,R,rson);
     int ans;
     ans=max(ta,tb);
     if(/*(s[mid]=='b'&&s[mid-1]=='w'&&s[mid+1]=='w')||*/(s[mid]=='w'&&s[mid+]=='b'&&s[mid+]=='w')&&mid+<=n) //同上
     {
         ans+=;
     }
     return ans;
 }
 int main()
 {
     int i,j,k;
     #ifndef ONLINE_JUDGE
     freopen("1.in","r",stdin);
     #endif
     scanf("%d",&tt);
     int ca=;
     while(tt--)
     {
         printf("Case %d:\n",ca++);
         scanf("%d%d",&n,&m);
         scanf("%s",s+);
         s[]='k';
         build(root);
         while(m--)
         {
             int op;
             scanf("%d",&op);
             if(op==)
             {
                 int l,r;
                 scanf("%d%d",&l,&r);
                 //printf("%d %d\n",l,r);
                 l++,r++;
                 int w=query(l,r,root);
                 printf("%d\n",w);
             }
             else
             {
                 int x,val;
                 char c[];
                 scanf("%d%s",&x,c);
                 x++;
                 if(c[]!=s[x])  s[x]=c[],update(x,val,root);

             }
         }
     }
 }

TLE代码