hdu 1698

一个语句顺序错了，我弄了2个小时才找到（细心才是王道）

这个题是线段树区间更新，区间查询

#include<stdio.h>
#include<algorithm>
#define maxn 100000*4+10
using namespace std;
struct node
{
    int l;
    int r;
    int value;
    int lazy;
} tr[maxn];
int a[maxn];
void pushup(int ro)
{
    tr[ro].value=tr[ro<<1].value+tr[ro<<1|1].value;
}
void pushdown(int ro)
{if(tr[ro].lazy > 0){
    tr[ro<<1].lazy=tr[ro].lazy;
    tr[ro<<1|1].lazy=tr[ro].lazy;
    tr[ro<<1].value=tr[ro].lazy*(tr[ro<<1].r-tr[ro<<1].l+1);
    tr[ro<<1|1].value=tr[ro].lazy*(tr[ro<<1|1].r-tr[ro<<1|1].l+1);
    tr[ro].lazy=0;}
}
void build(int ro,int l,int r)
{
    tr[ro].l=l;
    tr[ro].r=r;
    tr[ro].lazy=0;//就是这，浪费了我2个小时
    if(l==r)
    {
        tr[ro].value=a[l];

        return;
    }
    int mid=(l+r)/2;
    build(ro*2,l,mid);
    build(ro*2+1,mid+1,r);
    pushup(ro);
}
void update(int ro,int ll,int rr,int val)
{
    if(rr<tr[ro].l||ll>tr[ro].r)
        return ;
    if(tr[ro].l>=ll&&tr[ro].r<=rr)
    {
        tr[ro].lazy=val;
        tr[ro].value=val*(tr[ro].r-tr[ro].l+1);
        return;
    }
    pushdown(ro);
    int mid=(tr[ro].l+tr[ro].r)/2;
//    if(ll<=mid)//可要可不要
    update(ro*2,ll,rr,val);
//    if(rr>mid)//可要可不要
    update(ro*2+1,ll,rr,val);
   pushup(ro);
}

int  query(int ro,int l,int r)
{

    if(l<=tr[ro].l&&r>=tr[ro].r)
        return tr[ro].value;
    int mid=(tr[ro].l+tr[ro].r)/2;
    pushdown(ro);
    int res=0;
    if(r<=mid) res+=query(ro*2,l,r);
    else if(l>mid) res+=query(ro*2+1,l,r);
    else res+=query(ro*2,l,r)+query(ro*2+1,l,r);
    return res;
}
int main()
{
    int i,t1,t2,t3=1,n;
    int x,y,z;
    scanf("%d",&t1);
    while(t1--)
    {
        scanf("%d",&n);
        for(i=1; i<=n; i++)a[i]=1;
        build(1,1,n);
        scanf("%d",&t2);
        while(t2--)
        {
            scanf("%d%d%d",&x,&y,&z);
            update(1,x,y,z);
        }
        printf("Case %d: The total value of the hook is %d.\n",t3++,query(1,1,n));
    }
    return 0;
}

我参考的代码段：

/*
 线段树+修改区间+询问区间
 */
 #include<stdio.h>
 #include<string.h>
 #include<stdlib.h>
 #include<algorithm>
 #include<iostream>
 #include<queue>
 #include<vector>
 #include<map>
 #include<math.h>
 typedef long long ll;
 //typedef __int64 int64;
 const int maxn = 100005;
 const int maxm = 1005;
 const int inf = 0x7FFFFFFF;
 const double pi = acos(-1.0);
 const double eps = 1e-8;
 using namespace std;
 #define LEFT( x ) (x<<1)
 #define RIGHT( x ) ((x<<1)+1)
 struct node{
     int l,r,sum;
     int flag;
 }tree[ maxn<<2 ];
 int data[ maxn ];
 void pushup( int n ){
     tree[ n ].sum = tree[ LEFT( n ) ].sum+tree[ RIGHT( n ) ].sum;
     return ;
 }
 void pushdown( int n,int m ){//下标为n，这段区间有m个数
     if( tree[ n ].flag!=0 ){
         tree[ LEFT( n ) ].flag = tree[ RIGHT( n ) ].flag = tree[ n ].flag;
         tree[ LEFT( n ) ].sum =  tree[ n ].flag*(m-m/2);//tree[ n ].flag*((m+1)/2);
         tree[ RIGHT( n ) ].sum = tree[ n ].flag*(m/2);//tree[ n ].flag*( m-(m+1)/2 );
         tree[ n ].flag = 0;
     }
     return;
 }
 void build( int l,int r,int n ){
     if( l==r ){
         tree[ n ].sum = data[ l ];
         tree[ n ].flag = 0;
         tree[ n ].l=tree[ n ].r = l;
         return ;
     }
     tree[ n ].flag = 0;
     tree[ n ].l = l;
     tree[ n ].r = r;
     int mid;
     mid = (l+r)>>1;
     build( l,mid,LEFT( n ) );
     build( mid+1,r,RIGHT( n ) );
     pushup( n );
     return;
 }
 void update( int a,int b,int c,int l,int r,int n ){
     if( a==l&&b==r ){
         tree[ n ].flag = c;
         tree[ n ].sum = (r-l+1)*c;
         return ;
     }
     pushdown( n,r-l+1 );
     //printf("test\n");
     int mid;
     mid = (l+r)>>1;
     if( mid>=b ) update( a,b,c,l,mid,LEFT( n ) );
     else if( mid<a ) update( a,b,c,mid+1,r,RIGHT( n ));
     else {
         update( a,mid,c,l,mid,LEFT( n ) );
         update( mid+1,b,c,mid+1,r,RIGHT( n ) );
     }
     pushup( n );
     return ;
 }
 int query( int a,int b,int l,int r,int n ){
     if( a==l&&b==r ){
         return tree[ n ].sum;
     }
     pushdown( n,r-l+1 );
     int mid;
     mid = (l+r)>>1;
     if( mid>=b ) return query( a,b,l,mid,LEFT( n ) );
     else if( mid<a ) return query( a,b,mid+1,r,RIGHT( n ));
     else return query( a,mid,l,mid,LEFT( n ) )+query( mid+1,b,mid+1,r,RIGHT( n ));
 }
 int main(){
     int ca;
     scanf("%d",&ca);
     for( int t=1;t<=ca;t++ ){
         int n;
         scanf("%d",&n);
         for( int i=1;i<=n;i++ ){
             data[ i ] = 1;
         }
         build( 1,n,1 );
         int op;
         scanf("%d",&op);
         while( op-- ){
             int a,b,c;
             scanf("%d%d%d",&a,&b,&c);
             update( a,b,c,1,n,1 );
         }
         printf("Case %d: The total value of the hook is %d.\n",t,tree[ 1 ].sum);
     }
     return 0;
 }

贴上线段树延迟标记写法：

void pushup(int index){  
    tree[index].sum = tree[index<<1].sum+tree[index<<1|1].sum;  
    tree[index].mx = max(tree[index<<1].mx,tree[index<<1|1].mx);  
    tree[index].mn = min(tree[index<<1].mn,tree[index<<1|1].mn);  
}  
void pushdown(int index){  
    //说明该区间之前更新过  
    //要想更新该区间下面的子区间，就要把上次更新该区间的值向下更新  
    if(tree[index].add > 0){  
        //替换原来的值  
        /* 
        tree[index<<1].sum = (tree[index<<1].r-tree[index<<1].l+1)*tree[index].add; 
        tree[index<<1|1].sum = (tree[index<<1|1].r-tree[index<<1|1].l+1)*tree[index].add; 
        tree[index<<1].mx = tree[index].add; 
        tree[index<<1|1].mx = tree[index].add; 
        tree[index<<1].mn = tree[index].add; 
        tree[index<<1|1].mn = tree[index].add; 
        tree[index<<1].add = tree[index].add; 
        tree[index<<1|1].add = tree[index].add; 
        tree[index].add = 0;*/  
        //在原来的值的基础上加上val  
          
        tree[index<<1].sum += (tree[index<<1].r-tree[index<<1].l+1)*tree[index].add;  
        tree[index<<1|1].sum +=(tree[index<<1|1].r-tree[index<<1|1].l+1)*tree[index].add;  
        tree[index<<1].mx += tree[index].add;  
        tree[index<<1|1].mx += tree[index].add;  
        tree[index<<1].mn += tree[index].add;  
        tree[index<<1|1].mn += tree[index].add;  
        tree[index<<1].add += tree[index].add;  
        tree[index<<1|1].add += tree[index].add;  
        tree[index].add = 0;  
  
    }  
}