线段树(单点更新) POJ 2886 Who Gets the Most Candies?

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 << ];
 struct node
 {
     char name[];
     int val;
 }boy[MAX_N<<];
 int ans[MAX_N];
 int id;
 int n, k;

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

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

 void Solve(){   //计算ans
     memset(ans,,sizeof(ans));
     for(int i=;i<=n;i++){
         ans[i]++;
         for(int j=*i;j<=n;j+=i)
             ans[j]++;
     }
     int max=ans[];
     id=;
     for(int i=;i<=n;i++)   //找出第几个人跳出获得的糖最多
         if(ans[i]>max){
             max=ans[i];
             id=i;
         }
 }

 int main(void)      //POJ 2886 Who Gets the Most Candies?
 {
     //freopen ("inF.txt", "r", stdin);

     while (~scanf ("%d%d", &n, &k))
     {
         build (, n, );
         for (int i=; i<=n; ++i)
         {
             scanf ("%s%d", &boy[i].name, &boy[i].val);
             //printf ("%s%d\n", boy[i].name, boy[i].val);
         }
         Solve();
         //int maxn = f(n);
         int mod = sum[];
         boy[].val = ;
         int pos = ;
         //printf ("%d\n", id);
         int m=id;
         while (m--)
         {
             if (boy[pos].val > )
                 k=((k-+boy[pos].val-)%mod+mod)%mod+;
             else
                 k=((k-+boy[pos].val)%mod+mod)%mod+;
             pos = update (k, , n, );
             //printf ("%d ", pos);
             mod = sum[];
         }
         printf ("%s %d\n", boy[pos].name, ans[id]);
     }
 }