poj_2777_线段树

题目描述：

   在离散段上上色。求覆盖区域的颜色有几种。

 

解题思路：

  
基础线段树的建树+修改+查询的过程。注意查询并不一定要找到区间相等，只要包含区间并且有标志颜色即可。修改函数需要注意标记下移的时候需要注意是否原先已经有标记颜色。

ps：注意，a可能大于b

 

代码：

#include

#include

#define L 100001

#define T 31

typedef struct{

   int left, right;

   int value;

}SEGNODE;

SEGNODE seg_tree[5*L];

int c[T],l,t,o;

void buildSegTree(int l, int r, int index){

   seg_tree[index].left =
l;

   seg_tree[index].right =
r;

   seg_tree[index].value =
0;

  

   if(l!=r){

     
buildSegTree(l,(l+r)/2,2*index);

     
buildSegTree((l+r)/2+1,r,2*index+1);

   }

}

void changeSegTree(int l, int r, int index, int v){

   if(seg_tree[index].left == l
&& seg_tree[index].right == r){

     
seg_tree[index].value = v;

   }else{

     
if(seg_tree[index].value!=0){

         
seg_tree[2*index].value = seg_tree[index].value;

         
seg_tree[2*index+1].value = seg_tree[index].value;

         
seg_tree[index].value = 0;

     
}

     
if(l > (seg_tree[index].left + seg_tree[index].right)/2){

         
changeSegTree(l,r,2*index+1,v);    

     
}else if(r <= (seg_tree[index].left + seg_tree[index].right)/2
){

         
changeSegTree(l,r,2*index,v);

     
}else{

         
changeSegTree(l,(seg_tree[index].left +
seg_tree[index].right)/2,2*index,v);

         
changeSegTree((seg_tree[index].left + seg_tree[index].right)/2+1,
r, 2*index+1,v);

     
}

   }

}

void searchSegTree(int l, int r, int index){

    
if(l >= seg_tree[index].left && r <=
seg_tree[index].right){

        
if(seg_tree[index].value!=0){

           
c[seg_tree[index].value] = 1;

        
}else{

            
if(l > (seg_tree[index].left + seg_tree[index].right)/2){

                
searchSegTree(l,r,2*index+1);

            
}else if(r <= (seg_tree[index].left + seg_tree[index].right)/2
){

                
searchSegTree(l,r,2*index);

            
}else{

                
searchSegTree(l,(seg_tree[index].left +
seg_tree[index].right)/2,2*index);

                
searchSegTree((seg_tree[index].left +
seg_tree[index].right)/2+1,r,2*index+1);

            
}

        
}

    
}

}

main(){

   int
i,j,x,y,color,sum,tmp;

   char oper[2];

  

   scanf("%d %d %d",&l,
&t, &o);

   buildSegTree(1,l,1);

   seg_tree[1].value = 1;

  

   for(i=1;i<=o;i++){

      
scanf("%s",oper);

      
if(strcmp(oper,"C")==0){

         
scanf("%d %d %d",&x, &y, &color);

         
if(x>y){

            
tmp = x;

            
x = y;

            
y = tmp;

         
}

         
changeSegTree(x,y,1,color);

      
}else{

         
memset(c,0,sizeof(c));

         
scanf("%d %d",&x,&y);

         
if(x>y){

            
tmp = x;

            
x = y;

            
y = tmp;

         
}

         
searchSegTree(x,y,1);

         
sum = 0;

         

         
for(j=1;j<=t;j++)

            
if(c[j]==1){

               
sum ++;