POJ 2528 Mayor's posters

/*
按照大牛博客顺序做的题目 
以前离散化好好理解了下
注意离散化后
struct SegTree{
    int l, r;
    int color;
    int getMid(){
        return (l + r) >> 1;
    }
}tree[MAXN << 2];
中l，r不是原区间的坐标了，而是排序去重后数组中对应的下标
做这题问题不大 基本上1A 第一次数组开小了 囧.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define L(x) ((x) << 1)
#define R(x) ((x) << 1 | 1)
#define MAXN 100100

struct SegTree{
    int l, r;
    int color;
    int getMid(){
        return (l + r) >> 1;
    }
}tree[MAXN << 2];

struct Query{            //询问区间的数据结构
    int left, right;
}q[10010];
bool hash[10010];        //统计颜色用的
int bin[20020];

int cmp(const void *a, const void *b){
    return *(int *)a - *(int *)b;
}
int bs(int left, int right, int tar){    //二分查找区间坐标在bin中的位置
    while(left <= right){
        int mid = (left + right) >> 1;
        if(bin[mid] == tar)
            return mid;
        if(bin[mid] > tar)
            right = mid - 1;
        else
            left = mid + 1;
    }
}
void bulid(int left, int right, int t){
    tree[t].l = left;
    tree[t].r = right;
    tree[t].color = 0;
    if(left == right)
        return;
    int mid = tree[t].getMid();
    bulid(left, mid, L(t));
    bulid(mid + 1, right, R(t));
}
void insert(int left, int right, int color, int t){
    if(left <= tree[t].l && right >= tree[t].r){
        tree[t].color = color;
        return;
    }
    if(tree[t].color != -1){
        tree[L(t)].color = tree[R(t)].color = tree[t].color;
        tree[t].color = -1;
    }
    int mid = tree[t].getMid();
    if( right <= mid ){
        insert(left, right, color, L(t));
    } else if( left > mid ){
        insert(left, right, color, R(t));
    } else {
        insert(left, mid, color, L(t));
        insert(mid + 1, right, color, R(t));
    }
    if(tree[L(t)].color == tree[R(t)].color && tree[L(t)].color != -1){
        tree[t].color = tree[L(t)].color;
    }
}
int query(int t){
    if( tree[t].l == tree[t].r ){
        if( tree[t].color != -1 ){
            if( !hash[tree[t].color] ){
                hash[tree[t].color] = true;
                return 1;
            }
            else
                return 0;
        }
    }
    if( tree[t].color != -1 ){
        if( !hash[tree[t].color] ){
            hash[tree[t].color] = true;
            return 1;
        }
        else{
            return 0;
        }
    }
    return query(L(t)) + query(R(t));
}
int main(){
    int t, n;
    scanf("%d",&t);
    while( t-- ){
        int num = 1;
        scanf("%d",&n);
        for(int i = 1; i <= n; ++i){
            scanf("%d%d",&q[i].left, &q[i].right);
            bin[num++] = q[i].left;
            bin[num++] = q[i].right;
        }        
        //升序排序
        qsort(bin + 1, num - 1, sizeof(bin[0]), cmp);//bin从1开始 个数num-1个
        //去重
        int cnt = 1;
        for(int i = 2; i < num; ++i){
            if(bin[i] != bin[i - 1])
                bin[++cnt] = bin[i];
        }
        bulid(1, cnt, 1);
        for(int i = 1; i <= n; ++i){
            int l = bs(1, cnt, q[i].left);
            int r = bs(1, cnt, q[i].right);
            insert(l, r, i, 1);
        }
        memset(hash, false, sizeof(hash));
        hash[0] = true;
        printf("%d\n",query(1));
    }    
    return 0;
}