hdu 1754 I Hate It (Splay)

           点修改，区间查询。可以用线段树，也可以用Spaly树。用来练习Spaly树吧。。学习Splay树的话推荐一个博客：点击打开链接。

#include<algorithm>#include<iostream>#include<cstring>#include<cstdio>#include<cmath>using namespace std;const int N = 201000;const int INF = 0x3f3f3f3f;int pre[N], key[N], ch[N][2], root, res[N];//分别表示父结点，键值，左右孩子（0左1右），根结点//新建一个结点void NewNode(int r, int val){    pre[r] = r - 1;    res[r] = key[r] = val;    ch[r][0] = ch[r][1] = 0;    ch[r - 1][1] = r;}void Push_Up(int x){    res[x] = max(res[ch[x][0]], res[ch[x][1]]);    res[x] = max(res[x], key[x]);}//旋转，kind为1是右旋，为0是左旋void Rotate(int x, int kind){    int y = pre[x];    ch[y][!kind] = ch[x][kind];    pre[ch[x][kind]] = y;    if(pre[y])        ch[pre[y]][ch[pre[y]][1] == y] = x;    pre[x] = pre[y];    ch[x][kind] = y;    pre[y] = x;    Push_Up(y);}//Splay调整，将结点r调整到goal下面void Splay(int r, int goal){    while(pre[r] != goal)    {        if(pre[pre[r]] == goal) Rotate(r, ch[pre[r]][0] == r);        else        {            int y = pre[r];            int kind = ch[pre[y]][0] == y;            if(ch[y][kind] == r)            {                Rotate(r, !kind);                Rotate(r, kind);            }            else            {                Rotate(y, kind);                Rotate(r, kind);            }        }    }    if(goal == 0) root = r;}void Update(int r, int val){    Splay(r, 0);    key[r] = val;    Push_Up(r);}int Query(int l, int r){    Splay(l - 1, 0);    Splay(r + 1, l - 1);    return res[ch[r + 1][0]];}int main(){    int n, m, v, q;    char c[2];    while(scanf("%d%d", &n, &m) != EOF)    {        NewNode(1, -INF);        for(int i = 1; i <= n; i ++)        {            scanf("%d", &v);            NewNode(i + 1, v);        }        NewNode(n + 2, -INF);        for(int i = n + 2; i; i --)            Push_Up(i);        root = 1;        for(int i = 0; i < m; i ++)        {            scanf("%s%d%d", c, &q, &v);            if(c[0] == 'Q')                printf("%d\n", Query(q + 1, v + 1));            else Update(q + 1, v);        }    }    return 0;}