CDOJ1324-卿学姐与公主 【线段树点更新】

http://acm.uestc.edu.cn/#/problem/show/1324

卿学姐与公主

Time Limit: 2000/1000MS (Java/Others)     Memory Limit: 65535/65535KB (Java/Others)

 

 

某日，百无聊赖的卿学姐打开了某11区的某魔幻游戏

在这个魔幻的游戏里，生活着一个美丽的公主，但现在公主被关押在了魔王的城堡中。

英勇的卿学姐拔出利刃冲向了拯救公主的道路。

走过了荒野，翻越了高山，跨过了大洋，卿学姐来到了魔王的第一道城关。

在这个城关面前的是魔王的精锐部队，这些士兵成一字排开。

卿学姐的武器每次只能攻击一个士兵，并造成一定伤害，卿学姐想知道某时刻从L

到R

这个区间内，从开始到现在累计受伤最严重的士兵受到的伤害。

最开始每个士兵的受到的伤害都是0

Input

第一行两个整数N,Q表示总共有N个士兵编号从1到N，和Q个操作。

接下来Q行，每行三个整数，首先输入一个t，如果t是1，那么输入p,x，表示卿学姐攻击了p这个位置的士兵，并造成了x的伤害。如果t是2，那么输入L,R，表示卿学姐想知道现在[L,R]闭区间内，受伤最严重的士兵受到的伤害。

1≤N≤100000

1≤Q≤100000

1≤p≤N

1≤x≤100000

1≤L≤R≤N1≤L≤R≤

Output

对于每个询问，回答相应的值

Sample input and output

Sample Input	Sample Output
5 4 2 1 2 1 2 4 1 3 5 2 3 3	0 5

思路：线段树 点更新

代码：

 #include <fstream>
 #include <iostream>
 using namespace std;

 #define MAX 100005
 #define ll long long int

 class SegmentTree
 {
 private:
     int n;
     struct Node
     {
         int left, right, mid;
         ll maxval;
         Node (): maxval()
         {}
     }*tree;
 public:
     SegmentTree (int n): n(n)
     {
         tree = new Node[n<<];
     }
     ~SegmentTree ()
     {
         delete []tree;
     }
     void Build ();
     void Update (int id, int subid, int val);
     ll Search (int id, int left, int right);
 };
 void SegmentTree::Build () //非递归，由于叶子只能出现在树的最后两层，故而可以以tree[i].left < n作为循环条件进行非递归操作。需要说明的是，这里把最后一层的多余内存也初始化了，不过不影响全局。
 {
     int t1;
     tree[].left = ;
     tree[].right = n;
     tree[].mid = (n + ) >> ;
     for (int i = ; tree[i].left < n; i++)
     {
         if (tree[i].left < tree[i].right)
         {
             t1 = i << ;
             tree[t1].left = tree[i].left;
             tree[t1].right = tree[i].mid;
             tree[t1].mid = (tree[t1].left + tree[t1].right) >> ;
             t1++;
             tree[t1].left = tree[i].mid + ;
             tree[t1].right = tree[i].right;
             tree[t1].mid = (tree[t1].left + tree[t1].right) >> ;
         }
     }
 }
 void SegmentTree::Update (int id, int subid, int val)
 {
     if (tree[id].left == tree[id].right)
     {
         tree[id].maxval += val;
     }
     else if (tree[id].mid >= subid)
     {
         Update(id << , subid, val);
         tree[id].maxval = max(tree[id << ].maxval, tree[id].maxval);
     }
     else if (tree[id].mid < subid)
     {
         Update((id << )|, subid, val);
         tree[id].maxval = max(tree[id].maxval, tree[(id << )|].maxval);
     }
 }
 ll SegmentTree::Search (int id, int left, int right)
 {
     if (tree[id].left == left && tree[id].right == right)
     {
         return tree[id].maxval;
     }
     else if (tree[id].mid >= right)
     {
         return Search(id << , left, right);
     }
     else if (tree[id].mid < left)
     {
         return Search((id << )|, left, right);
     }
     else
     {
         return max(Search(id << , left, tree[id].mid), Search((id << )|, tree[id].mid + , right));
     }
 }

 int main ()
 {
     //freopen("D:\\input.in","r",stdin);
     int n, q, t, p, x;
     scanf ("%d %d", &n, &q);
     SegmentTree lv(n);
     lv.Build();
     for (int i = ; i < q; i++)
     {
         scanf ("%d %d %d", &t, &p, &x);
         if (t == )
         {
             lv.Update(, p, x);
         }
         else
         {
             printf("%lld\n", lv.Search(, p, x));
         }
     }
     return ;
 }

代码2：递归

 #include <fstream>
 #include <iostream>
 using namespace std;

 #define MAX 100005
 #define ll long long int

 class SegmentTree
 {
 private:
     int n;
     struct Node
     {
         int left, right, mid;
         ll maxval;
         Node (): maxval()
         {}
     }*tree;
 public:
     SegmentTree (int n): n(n)
     {
         tree = new Node[n<<];
     }
     ~SegmentTree ()
     {
         delete []tree;
     }
     void Build (int id, int left, int right);
     void Update (int id, int subid, int val);
     ll Search (int id, int left, int right);
 };
 void SegmentTree::Build (int id, int left, int right) //递归
 {
     tree[id].left = left;
     tree[id].right = right;
     tree[id].mid = (left + right) >> ;
     if (tree[id].mid == right)
     {
         return;
     }
     Build(id << , left, tree[id].mid);
     Build((id << )|, tree[id].mid + , right);
 }
 void SegmentTree::Update (int id, int subid, int val)
 {
     if (tree[id].left == tree[id].right)
     {
         tree[id].maxval += val;
     }
     else if (tree[id].mid >= subid)
     {
         Update(id << , subid, val);
         tree[id].maxval = max(tree[id << ].maxval, tree[id].maxval);
     }
     else if (tree[id].mid < subid)
     {
         Update((id << )|, subid, val);
         tree[id].maxval = max(tree[id].maxval, tree[(id << )|].maxval);
     }
 }
 ll SegmentTree::Search (int id, int left, int right)
 {
     if (tree[id].left == left && tree[id].right == right)
     {
         return tree[id].maxval;
     }
     else if (tree[id].mid >= right)
     {
         return Search(id << , left, right);
     }
     else if (tree[id].mid < left)
     {
         return Search((id << )|, left, right);
     }
     else
     {
         return max(Search(id << , left, tree[id].mid), Search((id << )|, tree[id].mid + , right));
     }
 }

 int main ()
 {
     //freopen("D:\\input.in","r",stdin);
     int n, q, t, p, x;
     scanf ("%d %d", &n, &q);
     SegmentTree lv(n);
     lv.Build(, , n);
     for (int i = ; i < q; i++)
     {
         scanf ("%d %d %d", &t, &p, &x);
         if (t == )
         {
             lv.Update(, p, x);
         }
         else
         {
             printf("%lld\n", lv.Search(, p, x));
         }
     }
     return ;
 }