CF356A Knight Tournament

对m个操作倒序进行操作，利用线段树实现区间赋值。

#include <bits/stdc++.h>
using namespace std;
const int N=3e5+5;
int n,m;
int l[N],r[N],x[N],sum[N<<2],add[N<<2],ans[N];

inline void pushdown(int k)
{
	if (add[k])
	{
		sum[k<<1]=sum[k<<1|1]=add[k];
		add[k<<1]=add[k<<1|1]=add[k];
		add[k]=0;
	}
}

void change(int k,int l,int r,int qx,int qy,int v)
{
	if (qx<=l && r<=qy)
	{
		sum[k]=v;
		add[k]=v;
		return;
	}
	pushdown(k);
	int mid=l+r>>1;
	if (qx<=mid) change(k<<1,l,mid,qx,qy,v);
	if (mid<qy) change(k<<1|1,mid+1,r,qx,qy,v);
}

void query(int k,int l,int r)
{
	if (l==r) 
	{
		ans[l]=sum[k];
		return;	
	}
	pushdown(k);
	int mid=l+r>>1;
	query(k<<1,l,mid);
	query(k<<1|1,mid+1,r);
}

int main(){
	scanf("%d%d",&n,&m);
	for (register int i=1; i<=m; ++i) scanf("%d%d%d",&l[i],&r[i],&x[i]);
	for (register int i=m; i>=1; --i)
	{
		if (l[i]<=x[i]-1) change(1,1,n,l[i],x[i]-1,x[i]);
		if (x[i]+1<=r[i]) change(1,1,n,x[i]+1,r[i],x[i]);
	}
	query(1,1,n);
	for (register int i=1; i<=n; ++i) printf("%d ",ans[i]);
return 0;
}