1764E - Doremy's Number Line - CodeForces Solution

#include "bits/stdc++.h"
using namespace std;

#define int long long
int mod = 1e9 + 7;
int inf = 1e17;

signed main()
{
	ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	
	int t;
	cin>>t;
	while(t--)
	{
		int n,k;
		cin>>n>>k;
		vector<vector<int>>a(n,vector<int>(3));
		for(int i=0;i<n;i++)
		{
			cin>>a[i][0]>>a[i][1];
			a[i][2] = i;
		}
		sort(a.begin(), a.end());
		int pos = 0;
		for(int i=0;i<n;i++)
		{
			if(a[i][2] == 0)
			{
				pos = i;
				break;
			}
		}
		if(a[pos][0]+a[pos][1] < k)
		{
			cout<<"NO\n";
			continue;
		}
		if(pos < n-1)
		{
			cout<<"YES\n";
			continue;
		}
		if(k <= a[pos][0])
		{
			cout<<"YES\n";
			continue;
		}
		int last = -inf;
		int mx = -1;
		for(int i=0;i<n-1;i++)
		{
			if(last >= a[i][0])
			{
				last = max(last, a[i][0]+a[i][1]);
			}
			else
			{
				last = max(last, last+a[i][1]);
			}
			last = max(last, a[i][0]);
			last = max(last, mx);
			mx = max(mx, a[i][0]+a[i][1]);
		}
		if(min(last,a[n-1][0]) + a[n-1][1] >= k) cout<<"YES\n";
		else cout<<"NO\n";

	}	

}