51nod 1402 最大值

#include <bits/stdc++.h>using namespace std;int arr[100100];int main(){int T,n,m,i,ans,x,t;cin>>T;while(T--){scanf("%d%d",&n,&m);for(i=1;i<=n;i++)arr[i]=i-1;for(i=0;i<m;i++){scanf("%d%d",&x,&t);arr[x]=min(arr[x],t);}for(i=2;i<=n;i++){arr[i]=min(arr[i-1]+1,arr[i]);}for(i=n-1;i>=1;i--){arr[i]=min(arr[i+1]+1,arr[i]);}ans=0;for(i=1;i<=n;i++)ans=max(ans,arr[i]);printf("%d\n",ans);}}