P1083 借教室

Posted 2020-11-15 hahaha2124652975

差分数组维护前缀和，之后从后往前判断是否合法，找到尽量位置在后的合法位置，判断输出就好了

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<cmath>
 5 #include<queue>
 6 #include<stack>
 7 #include<deque>
 8 #include<algorithm>
 9 #define ll long long
10 using namespace std;
11 const ll oo=0x3f3f3f3f;
12 const ll N=1000005;
13 
14 ll n,m,x=-1,sum;
15 ll a[N],c[N],l[N],r[N],cf[N];
16 bool flag=1;
17 
18 ll Min(ll a,ll b){return a<b?a:b;}
19 ll Max(ll a,ll b){return a>b?a:b;}
20 ll Abs(ll a){return a>0?a:-a;}
21 
22 ll get(){
23     char zy=getchar();
24     ll z=1,y=0;
25     while(zy>‘9‘||zy<‘0‘){
26         if(zy==‘-‘) z=-1;
27         zy=getchar();
28     }
29     while(zy>=‘0‘&&zy<=‘9‘){
30         y=(y<<1)+(y<<3)+zy-‘0‘;
31         zy=getchar();
32     }
33     return z*y;
34 }
35 
36 int main(){
37     n=get();m=get();
38     for(ll i=1;i<=n;i++) a[i]=get();
39     for(ll i=1;i<=m;i++){
40         c[i]=get();l[i]=get();r[i]=get();
41         cf[l[i]]+=c[i];
42         cf[r[i]+1]-=c[i];
43     }
44     ll j=m;
45     for(ll i=1;i<=n;i++){
46         sum+=cf[i];
47         if(sum>a[i]){
48             while(sum>a[i]){
49                 cf[l[j]]-=c[j];
50                 cf[r[j]+1]+=c[j];
51                 if(l[j]<=i&&i<=r[j]) sum-=c[j];
52                 j--;
53             }
54             if(flag){
55                 x=j;
56                 flag=0;
57             }
58             else x=min(x,j);
59         }
60     }
61     if(x==-1)printf("0
");
62     else printf("-1
%lld
",x+1);
63     return 0;
64 }