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");
}