pku2777 线段树 (位运算加速)

Count Color

有三个关键点，前两个和hdu1698一样

key1：记得将区间覆盖值置0时，将区间值赋给它的两个子区间

key2：当前区间cover不为0，即可return

key3：数据比较小，用位运算或操作，进行集合合并，加速过程。

 

#include<stdio.h>
#include<stdlib.h>
#define NN 100000
struct node{
       int l, r, mid, cover;       
}seg_tree[NN * 8];

void Init(int l, int r, int id){
     seg_tree[id].l = l;
     seg_tree[id].r = r;
     seg_tree[id].mid = (l + r) >> 1;
     seg_tree[id].cover = 1;
     
     if (r - l <= 1){
        return ;
     }
     
     Init(l, seg_tree[id].mid, id * 2);
     Init(seg_tree[id].mid, r, id * 2 + 1);
}

void Update(int l, int r, int key, int id){
     if (seg_tree[id].l == l && seg_tree[id].r == r){
        seg_tree[id].cover = key;
        return ;
     }
     //key 1
     if (seg_tree[id].cover != 0){
        seg_tree[id * 2].cover = seg_tree[id].cover;
        seg_tree[id * 2 + 1].cover = seg_tree[id].cover;
        seg_tree[id].cover = 0;
     }
     
     if (r <= seg_tree[id].mid){
        Update(l, r, key, id * 2);
     }else if (l >= seg_tree[id].mid){
           Update(l, r, key, id * 2 + 1);
     }else{
           Update(l, seg_tree[id].mid, key, id * 2);
           Update(seg_tree[id].mid, r, key, id * 2 + 1);
     }
}

int Search(int l, int r, int id){
    //key 2
    if (seg_tree[id].cover > 0){
       return 1 << seg_tree[id].cover;
    }
    
     if (r <= seg_tree[id].mid){
        return Search(l, r, id * 2);
     }else if (l >= seg_tree[id].mid){
           return Search(l, r, id * 2 + 1);
     }else{
           return Search(l, seg_tree[id].mid, id * 2) | Search(seg_tree[id].mid, r, id * 2 + 1);//key 3
     }
}
int main(){
    int L, T, O, a, b, c, cnt, ans;
    char str[3];
    scanf("%d%d%d", &L, &T, &O);
    Init(0, L, 1);
    while (O--){
          scanf("%s", str);
          if (str[0] == 'C'){
             scanf("%d%d%d", &a, &b, &c);
             Update(a - 1, b, c, 1);           
          }else{
                scanf("%d%d", &a, &b);
                ans = Search(a - 1, b, 1);
                cnt = 0;
                while (ans){
                      cnt += ans % 2;
                      ans /= 2;
                }
                printf("%d\n", cnt);      
          }
    }
    //system("pause");    
}