BZOJ3262/Luogu3810 陌上花开 (三维偏序,CDQ)

一个下午的光阴之死，凶手是细节与手残。
致命的一枪：BIT存权值时:

    for(; x <= maxx; x += x&-x) t[x] += w;
    //for(; x <= n; x += x&-x) t[x] += w;// You died 

int n;
int maxx;

struct Element{
    int a,b,c;
    long long ans;
    int siz;
    bool operator< (const Element &com)const{
        if(a != com.a) return a < com.a;
        if(b != com.b) return b < com.b;
        return c < com.c;
    }
}a[N],tmp[N];

long long t[N];
inline void Updata(int x, int w){
    for(; x <= maxx; x += x&-x) t[x] += w;
    //for(; x <= n; x += x&-x) t[x] += w;// You died 
}
inline long long Query(int x){
    long long s = 0;
    for(; x; x -= x&-x) s += t[x];
    return s;
}

inline void CDQ(int l,int r){
    if(l == r){
        a[l].ans += a[l].siz - 1;
        return;
    }
    int mid = (l + r) >> 1;
    CDQ(l, mid), CDQ(mid + 1, r);
    int i = l, j = mid + 1, k = l;
    while(i <= mid && j <= r){
        if(a[i].b <= a[j].b){
            Updata(a[i].c, a[i].siz);
            tmp[k++] = a[i++];
        }
        else{
            a[j].ans += Query(a[j].c);
            tmp[k++] = a[j++];
        }
    }
    while(j <= r) a[j].ans += Query(a[j].c), tmp[k++] = a[j++];
    R(j, l, i - 1) Updata(a[j].c, -a[j].siz);
    while(i <= mid) tmp[k++] = a[i++];
    
    R(i,l,r) a[i] = tmp[i];
}

long long tot[N];
int main(){
//  freopen("In.txt","r",stdin);
//  freopen("OUT.txt","w",stdout);
    io >> n >> maxx;
    R(i,1,n){
        io >> a[i].a >> a[i].b >> a[i].c;
    }
    
    sort(a + 1, a + n + 1);
    int cnt = 0;
    R(i,1,n){
        if(a[i].a == a[i-1].a && a[i].b == a[i-1].b && a[i].c == a[i-1].c && i != 1){
            ++a[cnt].siz;
        }
        else{
            a[++cnt] = a[i];
            a[cnt].siz = 1;
        }
    }

    
    CDQ(1, cnt);
    
    R(i,1,cnt){
        tot[a[i].ans] += a[i].siz;
    }
    
    --n;
    R(i,0,n){
        printf("%lld\n", tot[i]);
    }
    
    return 0;
}

BZOJ3262/Luogu3810 陌上花开 (三维偏序,CDQ)

原文：https://www.cnblogs.com/bingoyes/p/11181554.html