CodeForce 356A Knight Tournament（set应用）

 Knight Tournament

time limit per test

3 seconds

memory limit per test

256 megabytes

input

standard input

output

standard output

Hooray! Berl II, the king of Berland is making a knight tournament. The king has already sent the message to all knights in the kingdom and they in turn agreed to participate in this grand event.

As for you, you're just a simple peasant. There's no surprise that you slept in this morning and were late for the tournament (it was a weekend, after all). Now you are really curious about the results of the tournament. This time the tournament in Berland
went as follows:

• There are n knights participating in the tournament. Each knight was assigned his unique number — an integer from 1 to n.
• The tournament consisted of m fights, in the i-th
  fight the knights that were still in the game with numbers at least li and
  at most rihave
  fought for the right to continue taking part in the tournament.
• After the i-th fight among all participants of the fight only one knight won — the knight number xi,
  he continued participating in the tournament. Other knights left the tournament.
• The winner of the last (the m-th) fight (the knight number xm)
  became the winner of the tournament.

You fished out all the information about the fights from your friends. Now for each knight you want to know the name of the knight he was conquered by. We think that the knight number b was
conquered by the knight number a, if there was a fight with both of these knights present and the winner was the knight number a.

Write the code that calculates for each knight, the name of the knight that beat him.

Input

The first line contains two integers n, m (2 ≤ n ≤ 3·105; 1 ≤ m ≤ 3·105) —
the number of knights and the number of fights. Each of the following m lines contains three integers li, ri, xi (1 ≤ li < ri ≤ n; li ≤ xi ≤ ri) —
the description of the i-th fight.

It is guaranteed that the input is correct and matches the problem statement. It is guaranteed that at least two knights took part in each battle.

Output

Print n integers. If the i-th
knight lost, then the i-th number should equal the number of the knight that beat the knight number i.
If the i-th knight is the winner, then the i-th
number must equal 0.

Sample test(s)

input

4 3
1 2 1
1 3 3
1 4 4

output

3 1 4 0 

input

8 4
3 5 4
3 7 6
2 8 8
1 8 1

output

0 8 4 6 4 8 6 1 

Note

Consider the first test case. Knights 1 and 2 fought the first fight and knight 1 won. Knights 1 and 3 fought the second fight and knight 3 won. The last fight was between knights 3 and 4, knight 4 won.

题意：有n个人參加比赛，共同拥有m场比赛，每场比赛给出l,r,x,表示[l,r]区间内的人都被x打败，问最后每一个人是被谁打败的，输出那个人的编号，冠军输出0.

分析：这题能够用set，也能够用线段树做。

set解题方法：開始时把全部的人都加进去，然后把输了的人从set中删除就可以。

#include<iostream>
#include<set>
#include<cstring>
using namespace std;
const int MAXN = 300010;
int ans[MAXN];
set<int> s;
set<int>::iterator it, it_l, tmp[MAXN];
int main()
{
    int n, m, l, r, x, num;
    while(cin >> n >> m) {
        s.clear();
        memset(ans, 0, sizeof(ans));
        for(int i = 1; i <= n; i++)
            s.insert(i);
        for(int i = 0; i < m; i++) {
            cin >> l >> r >> x;
            it_l = s.lower_bound(l); //寻找開始删除的位置
            num = 0;
            for(it = it_l; *it <= r && it != s.end(); it++) {
                if(*it != x) {
                    ans[*it] = x;
                    tmp[num++] = it;  //不能直接删，由于每删除一个元素，set会自己主动调整内部结构
                }
            }
            for(int j = 0; j < num; j++)
                s.erase(tmp[j]);
        }
        for(int i = 1; i < n; i++)
            cout << ans[i] << " ";
        cout << ans[n] << endl;
    }
    return 0;
}