hdu 6301 Distinct Values (双指针,水题)

大意: 给定m个区间, 求构造一个长n且字典序最小的序列, 使得每个区间内的数各不相同

求出每个位置为左端点时向右延伸最大距离, 然后双指针, 每次从set中取最小

#include <iostream>
#include <algorithm>
#include <math.h>
#include <cstdio>
#include <set>
#include <map>
#include <string>
#include <vector>
#include <string.h>
#include <queue>
#define PER(i,a,n) for(int i=n;i>=a;--i)
#define REP(i,a,n) for(int i=a;i<=n;++i)
using namespace std;

const int N = 1e6+10;
int n, m, a[N], ans[N];
set<int> s;

void work() {
	scanf("%d%d", &n, &m);
	REP(i,1,n) a[i]=i;
	REP(i,1,m) {
		int l, r;
		scanf("%d%d", &l, &r);
		a[l] = max(a[l], r);
	}
	s.clear();
	REP(i,1,n) s.insert(i);
	int now = 1;
	REP(i,1,n) {
		while (now<=a[i]) { 
			ans[now++]=*s.begin();
			s.erase(s.begin());
		}
		s.insert(ans[i]);
	}
	REP(i,1,n) printf("%d%c",ans[i]," \n"[i==n]);
}

int main() {
	int t;
	scanf("%d", &t);
	while (t--) work();
}