luogu1083 [NOIp2012]借教室 (二份答案+差分)

 1 #include<bits/stdc++.h>
 2 #define pa pair<int,int>
 3 #define lowb(x) ((x)&(-(x)))
 4 #define REP(i,n0,n) for(i=n0;i<=n;i++)
 5 #define PER(i,n0,n) for(i=n;i>=n0;i--)
 6 #define MAX(a,b) ((a>b)?a:b)
 7 #define MIN(a,b) ((a<b)?a:b)
 8 #define CLR(a,x) memset(a,x,sizeof(a))
 9 #define rei register int
10 using namespace std;
11 typedef long long ll;
12 const int maxn=1e6+5;
13 
14 inline ll rd(){
15     ll x=0;char c=getchar();int neg=1;
16     while(c<‘0‘||c>‘9‘){if(c==‘-‘) neg=-1;c=getchar();}
17     while(c>=‘0‘&&c<=‘9‘) x=x*10+c-‘0‘,c=getchar();
18     return x*neg;
19 }
20 
21 int N,M,ask[maxn][3];
22 int num[maxn],cnt[maxn];
23 
24 inline bool judge(int m){
25     memset(cnt,0,sizeof(cnt));
26     for(int i=1;i<=m;i++){
27         cnt[ask[i][0]]+=ask[i][2],cnt[ask[i][1]+1]-=ask[i][2];
28     }
29     for(int i=1,j=0;i<=N;i++){
30         j+=cnt[i];
31         if(j>num[i]) return 0;
32     }return 1;
33 }
34 
35 int main(){
36     //freopen(".in","r",stdin);
37     rei i,j,k;
38     N=rd(),M=rd();
39     for(i=1;i<=N;i++) num[i]=rd();
40     for(i=1;i<=M;i++){
41         int a=rd(),b=rd(),c=rd();
42         ask[i][0]=b,ask[i][1]=c,ask[i][2]=a;
43     }
44     int l=0,r=M,ans;
45     while(l<=r){
46         int m=l+r>>1;
47         if(judge(m)) ans=m+1,l=m+1;
48         else ans=m,r=m-1;
49     }
50     if(ans>M) printf("0\n");
51     else{
52         printf("-1\n%d\n",ans);
53     }
54     return 0;
55 }