hdu 1754 I Hate It

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线段树的单点更新
详情请见代码：
#include<stdio.h>#include<stdlib.h>#include<string.h>#include<iostream>#include<algorithm>#define maxn 200100using namespace std;int sto[maxn<<2];int up[maxn<<2];void Insert(int left,int right,int o){    up[o]=0;    if(left==right)    {        scanf("%d",&sto[o]);        return ;    }    int lso=o<<1;    int mid=(left+right)>>1;    Insert(left,mid,lso);    Insert(mid+1,right,lso|1);    sto[o]=max(sto[lso],sto[lso|1]);}void changedata(int o){    if(up[0]!=0)    {        int lso=o<<1;        up[lso]=up[o];        up[lso|1]=up[o];        sto[lso]=up[o];        sto[lso|1]=up[o];        up[o]=0;    }}int getdata(int left,int right,int o,int begin,int end,int val){    if(begin<=left&&right<=end)    {        if(val!=1<<28)        {           up[o]=val;           sto[o]=val;        }        return sto[o];    }    changedata(o);    int lso=o<<1;    int mid=(right+left)>>1;    int ans=-1<<10;    if(begin<=mid)ans=max(ans,getdata(left,mid,lso,begin,end,val));    if(mid<end)ans=max(ans,getdata(mid+1,right,lso|1,begin,end,val));    sto[o]=max(sto[lso],sto[lso|1]);    return ans;}int main(){    int m,n;    while(~scanf("%d%d",&n,&m))    {        Insert(1,n,1);        char str[5];        int x,y;        for(int i=0;i<m;i++)        {            scanf("%s",str);            if(str[0]=='Q')            {                scanf("%d%d",&x,&y);                printf("%d\n",getdata(1,n,1,x,y,1<<28));            }            if(str[0]=='U')            {                scanf("%d%d",&x,&y);                int z=getdata(1,n,1,x,x,y);            }        }    }    return 0;}
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