线段树(单点更新) HDOJ 4288 Coder

题目传送门

 #include <cstdio>
 #include <cstring>
 #define lson l, m, rt << 1
 #define rson m + 1, r, rt << 1 | 1

 const int MAX_N =  + ;
 int sum[MAX_N << ];

 void pushup(int rt)
 {
     if (rt >>  %  == )
         sum[rt] += sum[rt >> ];
     if (rt >> |  %  == )
         sum[rt] += sum[rt >>  | ];
 }

 void build(int l, int r, int rt)
 {
     sum[rt] = r - l + ;
     if (l == r)
     {
         return ;
     }
     int m = (l + r) >> ;
     build (lson);
     build (rson);
     pushup (rt);
 }

 void update(int p, int l, int r, int rt)
 {
     if (l == r)
     {
         sum[rt] = p;
         return ;
     }
     int m = (l + r) >> ;
     if (p <= m)    update (p, lson);
     else    update (p, rson);

     pushup (rt);
 }

 int main(void)        //HDOJ 4288 Coder
 {
     //freopen ("inG.txt", "r", stdin);
     int n;
     char op[];
     int x;

     while (~scanf ("%d", &n))
     {
         build (, n, );
         while (n--)
         {
             scanf ("%s", &op);
             if (strcmp (op, "add") == )
             {
                 scanf ("%d", &x);
                 update (x, , n, );
             }
             if (strcmp (op, "del") == )
             {
                 scanf ("%d", &x);
                 update (-x, , n, );
             }
             if (strcmp (op, "sum") == )
             {
                 printf ("%d\n", sum[]);
             }
         }
     }

     return ;
 }