POJ

POJ - 2528 Mayor's posters

题意就是在墙上贴海报，给你每张海报覆盖的起始位置，求最后能看到几张海报

用线段树来做，-1表示未覆盖的和混合的

#include <stdio.h>#include <string.h>#include <iostream>#include <algorithm>#include <vector>#include <queue>#include <stack>#include <set>#include <map>#include <string>#include <math.h>#include <stdlib.h>#include <time.h>#include <bitset>#define INF 0x3f3f3f3f#define eps 1e-6#define PI 3.1415926#define mod 1000000009#define base 2333using namespace std;typedef long long LL;const int maxn = 1e5 + 10;const int maxx = 1e3 + 10;inline void splay(int &v) {    v=0;char c=0;int p=1;    while(c<'0' || c >'9'){if(c=='-')p=-1;c=getchar();}    while(c>='0' && c<='9'){v=(v<<3)+(v<<1)+c-'0';c=getchar();}    v*=p;}int t, n, x, y, ans, Hash[maxn], aa[maxn<<1];struct edge {    int l, r;    edge(int l = 0, int r = 0):        l(l), r(r) {}} seg[maxn];struct Tree {    int l, r, m;    int lazy, val;} tr[maxn<<2];void PushDown(int id) {    if(tr[id].lazy != -1) {        tr[id<<1].lazy = tr[id<<1|1].lazy = tr[id].lazy;        tr[id].lazy = -1;    }}void build(int id, int l, int r) {    tr[id].l = l, tr[id].r = r;    tr[id].m = (l+r)>>1;    if(l == r)        tr[id].lazy = -1;    else {        build(id<<1, l, tr[id].m);        build(id<<1|1, tr[id].m+1, r);        tr[id].val = tr[id].lazy = -1;    }}void update(int id, int l, int r, int v) {    if(l <= tr[id].l && r >= tr[id].r)        tr[id].lazy = v;    else {        PushDown(id);        if(l <= tr[id].m) update(id<<1, l, r, v);        if(r > tr[id].m) update(id<<1|1, l, r, v);    }}void query(int id, int l, int r) {    if(tr[id].lazy != -1) {        if(aa[tr[id].lazy] == 0) {            aa[tr[id].lazy] = 1;            ans++;        }        return ;    }    if(l == r)        return ;    else {        PushDown(id);        if(l <= tr[id].m) query(id<<1, l, r);        if(r > tr[id].m) query(id<<1|1, l, r);    }}void solve() {    splay(t);    while(t--) {        splay(n);        int k = 0, h = 0, m = 1;        ans = 0;        memset(aa, 0, sizeof(aa));        for(int i = 1; i <= n; i++) {            scanf("%d%d", &x, &y);            seg[++k] = edge(x, y);            Hash[++h] = x, Hash[++h] = y;        }        sort(Hash+1, Hash+h+1);        for(int i = 1; i < h; i++) {            if(Hash[i] != Hash[i+1])                Hash[++m] = Hash[i+1];        }        build(1, 1, m);        for(int i = 1; i <= k; i++) {            int L = lower_bound(Hash+1, Hash+m+1, seg[i].l)-Hash;            int R = lower_bound(Hash+1, Hash+m+1, seg[i].r)-Hash;            update(1, L, R, i);        }        query(1, 1, m);        printf("%d\n", ans);    }}int main() {    //srand(time(NULL));    //freopen("kingdom.in","r",stdin);    //freopen("kingdom.out","w",stdout);    solve();}