NOIP2012TG DAY2T2 借教室 二分

 1 #include<iostream>
 2 using namespace std;
 3 const int N=1000005;
 4 typedef long long LL;
 5 struct ask{
 6     int l,r,s;
 7 }xw[N];
 8 LL qz[N];
 9 int n,m,rs[N];
10 bool check(int day){
11     int i;
12     memset(qz,0,sizeof(qz));
13     for(i=1;i<=day;i++){
14         qz[xw[i].l]+=xw[i].s;
15         qz[xw[i].r+1]-=xw[i].s;
16     }
17     for(i=1;i<=n;i++){
18         qz[i]+=qz[i-1];
19         if(rs[i]<qz[i])
20             return false;
21     }
22     return true;
23 }
24 void read(int &x){
25     x=0;
26     char c=getchar();
27     while(c<‘0‘||c>‘9‘)c=getchar();
28     while(c>=‘0‘&&c<=‘9‘){
29         x=x*10+c-48;
30         c=getchar();
31     }
32 }
33 int main()
34 {
35     freopen("classroom.in","r",stdin);
36     freopen("classroom.out","w",stdout);
37     int i,lo,hi;
38     read(n),read(m);
39     for(i=1;i<=n;i++)read(rs[i]);
40     for(i=1;i<=m;i++)read(xw[i].s),read(xw[i].l),read(xw[i].r);
41     if(check(n)){
42         cout<<0;
43         return 0;
44     }
45     lo=1,hi=n;
46     while(lo<hi){
47         int mid=(lo+hi)>>1;
48         if(check(mid))
49             lo=mid+1;
50         else
51             hi=mid;
52     }
53     cout<<-1<<endl<<lo;
54     return 0;
55 }