E. Turn Off The TV Educational Codeforces Round 29

http://codeforces.com/contest/863/problem/E

注意细节

 #include <cstdio>
 #include <cstdlib>
 #include <cmath>
 #include <cstring>
 #include <time.h>
 #include <string>
 #include <set>
 #include <map>
 #include <list>
 #include <stack>
 #include <queue>
 #include <vector>
 #include <bitset>
 #include <ext/rope>
 #include <algorithm>
 #include <iostream>
 using namespace std;
 #define ll long long
 #define minv 1e-6
 #define inf 1e9
 #define pi 3.1415926536
 #define E  2.7182818284
 const ll mod=1e9+;//
 const int maxn=2e5+;

 struct node
 {
     int x,y,z;
 }f[maxn];

 bool vis[maxn]={};

 int cmp(node a,node b)
 {
     if (a.x==b.x)
         return a.y>b.y;
     else
         return a.x<b.x;
 }

 int main()
 {
     int n,i,j,yy;
     scanf("%d",&n);
     for (i=;i<=n;i++)
         scanf("%d%d",&f[i].x,&f[i].y),f[i].z=i;
     sort(f+,f+n+,cmp);
     vis[f[].z]=;
     j=;
     for (i=;i<=n;)
     {
         yy=f[j].y+;
         i++;
         j=i;
         while (i<=n && f[i].x<=yy)
         {
             if (f[i].y>f[j].y)
                 j=i;
             i++;
         }
         if (f[j].y<=yy-)
             j=i;
         else
             i--;
         vis[f[j].z]=;
     }
     for (i=;i<=n;i++)
         if (!vis[i])
         {
             printf("%d",i);
             return ;
         }
     printf("-1");
     return ;
 }
 /*
 3

 3687 7959

 4918 9822

 8049 11728
 */