題目連結
Problem Description
Chiaki has an array of n positive integers. You are told some facts about the array: for every two elements ai and aj in the subarray al..r (1≤i≤r,1≤j≤r,j>i), ai≠aj holds.
Chiaki would like to find a lexicographically minimal array which meets the facts.

Input
There are multiple test cases. The first line of input contains an integer T, indicating the number of test cases. For each test case:
The first line contains two integers n and m (1≤n,m≤105) – the length of the array and the number of facts. Each of the next m lines contains two integers li and ri (1≤li≤ri≤n).
It is guaranteed that neither the sum of all n nor the sum of all m exceeds 106.

Output
For each test case, output n integers denoting the lexicographically minimal array. Integers should be separated by a single space, and no extra spaces are allowed at the end of lines.

Sample Input
3
2 1
1 2
4 2
1 2
3 4
5 2
1 3
2 4

Sample Output
1 2
1 2 1 2
1 2 3 1 1
題意分析：

#include <iostream>
#include <set>
#include <cstdio>
 

using namespace std;
int a[10010],pre[10010];
int main()
{
    int n,m,i,l,r,t;
    cin >> t;
    while(t--)
    {
        int flag=1;
        set<int>s;
        cin >> n >> m;
        for(i=1; i<=n; i++)
        {
            pre[i]=i;///初始化為1.2.3.....
            s.insert(i);///set裡面也是
        }
        while(m--)
        {
            cin >> l >> r;
            pre[r]=(pre[r]<l)?pre[r]:l;///進入小的
        }
        for(i=n-1; i>=1; i--)
            pre[i]=(pre[i]<pre[i+1])?pre[i]:pre[i+1];///左界的推移
        for(i=1; i<=n; i++)
        {
            while(flag < pre[i])
            {
                s.insert(a[flag]);
                flag++;
            }
            a[i]=*s.begin();///賦值
            s.erase(a[i]);///擦除
        }
        cout << a[1];
        for(i=2; i<=n; i++)
        {
            printf(" %d",a[i]);
        }
        cout << endl;
    }
    return 0;
}