Create 1190-SubarraySumQueries.cpp

Author: manitajay

RANGE Queries/cses/1190-SubarraySumQueries.cpp

@@ -0,0 +1,99 @@
+// JAI BAJARANG BALI
+
+// manitianajay45
+
+// give me some sunshine, give me some rain ,give me another chance to grow up once again....
+
+// sab moh maya hai....
+
+#include <bits/stdc++.h>
+using namespace std;
+
+#define ll long long
+
+
+struct node{
+ ll prefix,suffix,mx,total;
+};
+
+vector<node> seg(800005, {0,0,0,0});
+
+
+node merge(node a,node b){
+ node c;
+ c.prefix=max(a.total+b.prefix,a.prefix);
+ c.suffix=max(a.suffix+b.total,b.suffix);
+ c.total=a.total+b.total;
+ c.mx=max(a.mx,b.mx);
+ c.mx=max(c.mx,c.suffix);
+ c.mx=max(c.mx,c.prefix);
+ c.mx=max(c.mx,a.suffix+b.prefix);
+ return c;
+}
+
+
+
+void set1(ll i,ll val,ll x,ll l,ll r){
+ if(r-l==1){
+ seg[x].total=val;
+ seg[x].mx=max(0ll,val);
+ seg[x].prefix=max(0ll,val);
+ seg[x].suffix=max(0ll,val);
+ return ;
+ }
+ ll mid=(l+r)/2;
+
+ if(i<mid){
+ set1(i,val,2*x+1,l,mid);
+ }else{
+ set1(i,val,2*x+2,mid,r);
+ }
+ seg[x]=merge(seg[2*x+1],seg[2*x+2]);
+}
+
+
+node ans(ll l,ll r,ll x,ll lf,ll rf){
+ if(lf>=l && rf<=r){
+ return seg[x];
+ }else if(lf>=r || rf<=l){
+ return {0,0,0,0};
+ }
+ ll mid=(lf+rf)/2;
+ return merge(ans(l,r,2*x+1,lf,mid),ans(l,r,2*x+2,mid,rf));
+}
+
+
+
+
+
+int main()
+{
+
+ ios_base::sync_with_stdio(false);
+
+ cin.tie(NULL);
+
+ ll n, q;
+ cin >> n >> q;
+ 
+ for (ll i = 0; i < n; i++)
+ {
+ ll x;
+ cin>>x;
+
+ set1(i,x,0,0,n);
+ }
+
+ while(q--){
+ ll i,u;
+ cin>>i>>u;
+ i--;
+ set1(i,u,0,0,n);
+ 
+ 
+ 
+ node an=ans(0,n,0,0,n);
+ cout<<an.mx<<endl;
+ }
+ return 0;
+}