线段树(单点更新) POJ 2828 Buy tickets

题目传送门

 /*
     结点存储下面有几个空位
     每次从根结点往下找找到该插入的位置，
     同时更新每个节点的值
 */
 #include <cstdio>
 #define lson l, m, rt << 1
 #define rson m+1, r, rt << 1 | 1

 const int MAX_N =  + ;
 int pos[MAX_N], val[MAX_N];
 int sum[MAX_N << ];
 int que[MAX_N];
 int id;

 void build(int l, int r, int rt)
 {
     sum[rt] = r - l + ;        //节点有多少个空位置
     if (l == r)        return ;
     int m = (l + r) >> ;
     build (lson);
     build (rson);
 }

 void update(int p, int l, int r, int rt)
 {
     sum[rt]--;                    //插入一个减少一个空位置
     if (l == r)                    //找到了传递该位置
     {
         id = l;
         return ;
     }
     int m = (l + r) >> ;
     if (p <= sum[rt<<])
     {
         update (p, lson);
     }
     else
     {
         p -= sum[rt<<];    //减去
         update (p, rson);
     }
 }

 int main(void)        //POJ 2828 Buy tickets
 {
     //freopen ("inE.txt", "r", stdin);
     int n;

     while (~scanf ("%d", &n))
     {
         build (, n, );
         for (int i=; i<=n; ++i)
         {
             scanf ("%d%d", &pos[i], &val[i]);
         }
         for (int i=n; i>=; --i)        //最后插入的位置不变
         {
             update (pos[i]+, , n, );
             que[id] = val[i];
         }
         printf ("%d", que[]);
         for (int i=; i<=n; ++i)
         {
             printf (" %d", que[i]);
         }
         puts ("");
     }

     return ;
 }