POJ - 3470 Walls

小鸟往四个方向飞都枚举一下，数据范围没给，离散以后按在其中一个轴线排序，在线段树上更新墙的id，然后就是点查询在在哪个墙上了。

这题有个trick，因为数据范围没给我老以为是inf设置小了，WA了很多发。（距离可能比0x3f3f3f3f大

实现上，我是把鸟和墙的坐标放一起的，用下标来区别两者。

/*********************************************************
*            ------------------                          *
*   author AbyssalFish                                   *
**********************************************************/
#include<cstdio>
#include<iostream>
#include<string>
#include<cstring>
#include<queue>
#include<vector>
#include<stack>
#include<vector>
#include<map>
#include<set>
#include<algorithm>
#include<cmath>
#include<numeric>
#include<cassert>
using namespace std;typedef long long ll;
const int MAX_N = 5e4+5;
int N, M;
int dist[MAX_N];
int fly_to[MAX_N];
int wall_cnt[MAX_N];const int MAX_SIZE = MAX_N*3;
int x[MAX_SIZE], y[MAX_SIZE];
int rx[MAX_SIZE], ry[MAX_SIZE];
int xs[MAX_SIZE], ys[MAX_SIZE];//discrete data
int mpx[MAX_SIZE], mpy[MAX_SIZE];//用于离散idx访问原值
int sp, dat_sz;int *fi;//, *se;
bool cmp(int a, int b)
{return fi[a] < fi[b];// || (fi[a] == fi[b] && se[a] < se[b]);
}/*
parameter :
原始数据dat , 名次r ,size, 离散数据 a
*/void compress(int *dat, int *r, int sz, int *a, int *mp)//int *dat_
{for(int i = 0; i < sz; i++){r[i] = i;}fi = dat; //se = dat_;sort(r,r+sz,cmp);mp[a[r[0]] = 1] = dat[r[0]];for(int i = 1; i < sz; i++){int k = r[i], p = r[i-1];if(dat[k] != dat[p]){mp[ a[k] = a[p]+1 ] = dat[k];}else {a[k] = a[p];}}
}void init()
{// wall [0 N*2), bird [N*2, Ui)sp = N*2; dat_sz = sp+M;for(int i = 0; i < dat_sz; i++){scanf("%d%d", x+i, y+i);}compress(x, rx, dat_sz, xs, mpx);compress(y, ry, dat_sz, ys, mpy);
}#define para int o = 1, int l = 1,int r = n0
#define Tvar int mid = (l+r)>>1, lc = (o<<1), rc = (o<<1|1);
#define lsn lc, l, mid
#define rsn rc, mid+1, r
#define insd ql<=l&&r<=qr
const int ST_SIZE = 1<<19;int cv[ST_SIZE];
//完整覆盖，wall的idx , 不完整覆盖 -1,  完全无覆盖 0
int n0;
int qpos;int query(para)
{if(~cv[o]) return cv[o];else {Tvarreturn qpos <= mid? query(lsn) : query(rsn);}
}int ql, qr, qval;void update(para)
{if(insd){cv[o] = qval;}else {Tvarif(~cv[o]) {cv[lc] = cv[rc] = cv[o];cv[o] = -1;}if(ql <= mid) update(lsn);if(qr > mid) update(rsn);}
}void sweep_line(int k, int *ys, int *xs, int *mpy)
{if(k < sp){int k2 = k^1;//trick 小鸟可能在墙的延迟线上，害得我WA了无数发 T_Tif((xs[k2] >= xs[k])){qval = (k>>1)+1;ql = xs[k]; qr = xs[k2];update();}}else {qpos = xs[k];int w_id = query();//assert(w_id != -1);if(w_id) {w_id--;int pos_b = mpy[ys[k]];int d = min( abs(pos_b - mpy[ys[w_id<<1]]), abs(pos_b - mpy[ys[w_id<<1|1]]) );k -= sp;if(d < dist[k]){dist[k] = d; fly_to[k] = w_id;}}}
}void fly(int *ry, int *ys, int *xs, int *mpy, int mxx)
{n0 = mxx;ql = 1; qr = n0; qval = 0;update();for(int i = 0; i < dat_sz; i++){sweep_line(ry[i],ys,xs,mpy);}ql = 1; qr = n0; qval = 0;update();for(int i = dat_sz-1; i >= 0; i--){sweep_line(ry[i],ys,xs,mpy);}
}void solve()
{//memset(ans,0x3f,sizeof(ll)*M);fill(dist, dist+M, 0x7fffffff);fly(ry,ys,xs,mpy,xs[rx[dat_sz-1]]);fly(rx,xs,ys,mpx,ys[ry[dat_sz-1]]);memset(wall_cnt,0,sizeof(int)*N);for(int i = 0; i < M; i++) wall_cnt[fly_to[i]]++;for(int i = 0; i < N; i++){printf("%d\n", wall_cnt[i]);}
}//#define LOCAL
int main()
{
#ifdef LOCALfreopen("in.txt","r",stdin);
#endif//cout<<((int)ceil(log2(15e4))+1);while(~scanf("%d%d", &N, &M)){//assert(N<=MAX_N && M <= MAX_N);
        init();solve();}return 0;
}