poj_2777_線段樹

題目描述：

   在離散段上上色。求覆蓋區域的顏色有幾種。

 

解題思路：

   基礎線段樹的建樹+修改+查詢的過程。注意查詢並不一定要找到區間相等，只要包含區間並且有標誌顏色即可。修改函數需要注意標記下移的時候需要注意是否原先已經有標記顏色。

ps：注意，a可能大於b

 

代碼：

#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 ++;