From 4e5ca336e28c0a4669a8db2189676c3ebc5e4366 Mon Sep 17 00:00:00 2001
From: suzzzal <kshatrisujal@gmail.com>
Date: Thu, 1 Jan 2026 10:21:38 +0530
Subject: [PATCH 1/8] Create b_reverse_sort.cpp

---
 .../PrefixSum/soln/Sujal/b_reverse_sort.cpp   | 49 +++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 algos/range_queries/PrefixSum/soln/Sujal/b_reverse_sort.cpp

diff --git a/algos/range_queries/PrefixSum/soln/Sujal/b_reverse_sort.cpp b/algos/range_queries/PrefixSum/soln/Sujal/b_reverse_sort.cpp
new file mode 100644
index 0000000..b1c8ffb
--- /dev/null
+++ b/algos/range_queries/PrefixSum/soln/Sujal/b_reverse_sort.cpp
@@ -0,0 +1,49 @@
+//PROBLEM STATEMENT- https://codeforces.com/problemset/problem/1605/B
+//SUBMISSION LINK- https://codeforces.com/problemset/submission/1605/356028086
+//APPROACH- For every gap, check the ones on left and zeroes on right using prefix and suffix sums
+//          if at any point, they are equal(and non zero), they can be swapped
+//TIME COMPLEXITY- O(n*n)
+//SPACE COMPLEXITY- O(n*n)
+
+
+
+
+#include<bits/stdc++.h>
+using namespace std;
+
+void solve(){
+    int n;cin>>n;
+    string s;cin>>s;
+    if(n==1){cout<<0<<"\n";return;}
+
+    vector<vector<int>> L(n-1),R(n-1);
+
+    if(s[0]=='1')L[0].push_back(0);
+    for(int i=1;i<n-1;i++){
+        L[i]=L[i-1];
+        if(s[i]=='1')L[i].push_back(i);
+    }
+
+    if(s[n-1]=='0')R[n-2].push_back(n-1);
+    for(int i=n-2;i>0;i--){
+        R[i-1]=R[i];
+        if(s[i]=='0')R[i-1].push_back(i);
+    }
+
+    for(int i=0;i<n-1;i++){
+        int a=L[i].size(),b=R[i].size();
+        if(a==b&&a){
+            cout<<1<<"\n"<<a+b<<" ";
+            for(int x:L[i])cout<<x+1<<" ";
+            for(auto it=R[i].rbegin();it!=R[i].rend();it++)cout<<*it+1<<" ";
+            cout<<"\n";
+            return;
+        }
+    }
+    cout<<0<<"\n";
+}
+
+int main(){
+    int t;cin>>t;
+    while(t--)solve();
+}

From cda1ece330293e612e8636f77c23385a5c5dc974 Mon Sep 17 00:00:00 2001
From: suzzzal <kshatrisujal@gmail.com>
Date: Thu, 1 Jan 2026 10:23:50 +0530
Subject: [PATCH 2/8] Update b_reverse_sort.cpp

---
 algos/range_queries/PrefixSum/soln/Sujal/b_reverse_sort.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/algos/range_queries/PrefixSum/soln/Sujal/b_reverse_sort.cpp b/algos/range_queries/PrefixSum/soln/Sujal/b_reverse_sort.cpp
index b1c8ffb..53ff766 100644
--- a/algos/range_queries/PrefixSum/soln/Sujal/b_reverse_sort.cpp
+++ b/algos/range_queries/PrefixSum/soln/Sujal/b_reverse_sort.cpp
@@ -1,5 +1,7 @@
 //PROBLEM STATEMENT- https://codeforces.com/problemset/problem/1605/B
-//SUBMISSION LINK- https://codeforces.com/problemset/submission/1605/356028086
+
+//SUBMISSION LINK- https://codeforces.com/problemset/submission/1605/356028420
+
 //APPROACH- For every gap, check the ones on left and zeroes on right using prefix and suffix sums
 //          if at any point, they are equal(and non zero), they can be swapped
 //TIME COMPLEXITY- O(n*n)

From 94f7714750d09e877dc04f8fed5d43ef6674d46d Mon Sep 17 00:00:00 2001
From: suzzzal <kshatrisujal@gmail.com>
Date: Thu, 1 Jan 2026 10:27:08 +0530
Subject: [PATCH 3/8] Create tracking_segments.cpp

---
 .../soln/Sujal/tracking_segments.cpp          | 53 +++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 algos/range_queries/PrefixSum/soln/Sujal/tracking_segments.cpp

diff --git a/algos/range_queries/PrefixSum/soln/Sujal/tracking_segments.cpp b/algos/range_queries/PrefixSum/soln/Sujal/tracking_segments.cpp
new file mode 100644
index 0000000..f80b661
--- /dev/null
+++ b/algos/range_queries/PrefixSum/soln/Sujal/tracking_segments.cpp
@@ -0,0 +1,53 @@
+//PROBLEM STATEMENT- https://codeforces.com/problemset/problem/1843/E
+
+//SUBMISSION LINK- https://codeforces.com/problemset/submission/1843/356028549
+
+
+//APPROACH- Standard binary search on queries as they are monotonues (F F F T T TT)
+//TIME COMPLEXITY- O(nlogn)
+//SPACE COMPLEXITY- O(n)
+
+
+
+
+#include<bits/stdc++.h>
+using namespace std;
+
+bool ok(vector<pair<int,int>>&seg,vector<int>&q,int mid,int n){
+    vector<int>a(n,0);
+    for(int i=0;i<mid;i++)a[q[i]-1]=1;
+
+    vector<int>pre(n+1,0);
+    for(int i=0;i<n;i++)pre[i+1]=pre[i]+a[i];
+
+    for(auto &p:seg){
+        if(pre[p.second]-pre[p.first-1]>(p.second-p.first+1)/2)
+            return true;
+    }
+    return false;
+}
+
+void solve(){
+    int n,m;cin>>n>>m;
+    vector<pair<int,int>>seg(m);
+    for(int i=0;i<m;i++)cin>>seg[i].first>>seg[i].second;
+
+    int qn;cin>>qn;
+    vector<int>q(qn);
+    for(int i=0;i<qn;i++)cin>>q[i];
+
+    int l=1,r=qn,ans=-1;
+    while(l<=r){
+        int mid=(l+r)/2;
+        if(ok(seg,q,mid,n)){
+            ans=mid;
+            r=mid-1;
+        }else l=mid+1;
+    }
+    cout<<ans<<"\n";
+}
+
+int main(){
+    int t;cin>>t;
+    while(t--)solve();
+}

From 3d3b9c90d659785bbdf68f280cb11fe0435270d1 Mon Sep 17 00:00:00 2001
From: suzzzal <kshatrisujal@gmail.com>
Date: Thu, 1 Jan 2026 10:56:04 +0530
Subject: [PATCH 4/8] Create solution1.cpp

---
 .../DifferenceArray/soln/Sujal/solution1.cpp  | 87 +++++++++++++++++++
 1 file changed, 87 insertions(+)
 create mode 100644 algos/range_queries/DifferenceArray/soln/Sujal/solution1.cpp

diff --git a/algos/range_queries/DifferenceArray/soln/Sujal/solution1.cpp b/algos/range_queries/DifferenceArray/soln/Sujal/solution1.cpp
new file mode 100644
index 0000000..13f40fe
--- /dev/null
+++ b/algos/range_queries/DifferenceArray/soln/Sujal/solution1.cpp
@@ -0,0 +1,87 @@
+//submission link - https://cses.fi/problemset/result/15793543/
+
+
+/*
+Problem:
+You are given an array of n integers.
+You need to process q queries of two types:
+1) Add value u to all elements in range [a, b]
+2) Print the value at position k
+
+Queries are mixed and can come in any order.
+
+Approach:
+We use a Fenwick Tree (Binary Indexed Tree).
+
+Idea:
+- We convert range update into two point updates:
+    add u at index a
+    subtract u at index b+1
+- Fenwick Tree stores these updates.
+- For query type 2, we take prefix sum up to k
+  and add it to the original value at index k.
+
+This works because prefix sum gives
+the total update applied to that position.
+
+Time Complexity:
+- Each update: O(log n)
+- Each query: O(log n)
+- Total: O((n + q) log n)
+
+Space Complexity:
+- O(n)
+*/
+
+#include<bits/stdc++.h>
+using namespace std;
+
+struct Fenwick{
+    int n;
+    vector<long long> bit;
+
+    Fenwick(int n):n(n),bit(n+1,0){}
+
+    void add(int i,long long v){
+        for(;i<=n;i+=i&-i)
+            bit[i]+=v;
+    }
+
+    long long sum(int i){
+        long long s=0;
+        for(;i>0;i-=i&-i)
+            s+=bit[i];
+        return s;
+    }
+};
+
+int main(){
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n,q;
+    cin>>n>>q;
+
+    vector<long long>x(n+1);
+    for(int i=1;i<=n;i++)
+        cin>>x[i];
+
+    Fenwick fw(n+1);
+
+    while(q--){
+        int type;
+        cin>>type;
+
+        if(type==1){
+            int a,b;
+            long long u;
+            cin>>a>>b>>u;
+            fw.add(a,u);
+            fw.add(b+1,-u);
+        }else{
+            int k;
+            cin>>k;
+            cout<<x[k]+fw.sum(k)<<"\n";
+        }
+    }
+}

From 59012dd29e45942d4056de8080263942b796449e Mon Sep 17 00:00:00 2001
From: suzzzal <kshatrisujal@gmail.com>
Date: Thu, 1 Jan 2026 10:57:59 +0530
Subject: [PATCH 5/8] Update b_reverse_sort.cpp

---
 .../PrefixSum/soln/Sujal/b_reverse_sort.cpp   | 50 -------------------
 1 file changed, 50 deletions(-)

diff --git a/algos/range_queries/PrefixSum/soln/Sujal/b_reverse_sort.cpp b/algos/range_queries/PrefixSum/soln/Sujal/b_reverse_sort.cpp
index 53ff766..8b13789 100644
--- a/algos/range_queries/PrefixSum/soln/Sujal/b_reverse_sort.cpp
+++ b/algos/range_queries/PrefixSum/soln/Sujal/b_reverse_sort.cpp
@@ -1,51 +1 @@
-//PROBLEM STATEMENT- https://codeforces.com/problemset/problem/1605/B
 
-//SUBMISSION LINK- https://codeforces.com/problemset/submission/1605/356028420
-
-//APPROACH- For every gap, check the ones on left and zeroes on right using prefix and suffix sums
-//          if at any point, they are equal(and non zero), they can be swapped
-//TIME COMPLEXITY- O(n*n)
-//SPACE COMPLEXITY- O(n*n)
-
-
-
-
-#include<bits/stdc++.h>
-using namespace std;
-
-void solve(){
-    int n;cin>>n;
-    string s;cin>>s;
-    if(n==1){cout<<0<<"\n";return;}
-
-    vector<vector<int>> L(n-1),R(n-1);
-
-    if(s[0]=='1')L[0].push_back(0);
-    for(int i=1;i<n-1;i++){
-        L[i]=L[i-1];
-        if(s[i]=='1')L[i].push_back(i);
-    }
-
-    if(s[n-1]=='0')R[n-2].push_back(n-1);
-    for(int i=n-2;i>0;i--){
-        R[i-1]=R[i];
-        if(s[i]=='0')R[i-1].push_back(i);
-    }
-
-    for(int i=0;i<n-1;i++){
-        int a=L[i].size(),b=R[i].size();
-        if(a==b&&a){
-            cout<<1<<"\n"<<a+b<<" ";
-            for(int x:L[i])cout<<x+1<<" ";
-            for(auto it=R[i].rbegin();it!=R[i].rend();it++)cout<<*it+1<<" ";
-            cout<<"\n";
-            return;
-        }
-    }
-    cout<<0<<"\n";
-}
-
-int main(){
-    int t;cin>>t;
-    while(t--)solve();
-}

From d5def24f4f0f4602d9ee3a3d860df436aa070bf1 Mon Sep 17 00:00:00 2001
From: suzzzal <kshatrisujal@gmail.com>
Date: Thu, 1 Jan 2026 10:58:17 +0530
Subject: [PATCH 6/8] Update tracking_segments.cpp

---
 .../soln/Sujal/tracking_segments.cpp          | 52 -------------------
 1 file changed, 52 deletions(-)

diff --git a/algos/range_queries/PrefixSum/soln/Sujal/tracking_segments.cpp b/algos/range_queries/PrefixSum/soln/Sujal/tracking_segments.cpp
index f80b661..8b13789 100644
--- a/algos/range_queries/PrefixSum/soln/Sujal/tracking_segments.cpp
+++ b/algos/range_queries/PrefixSum/soln/Sujal/tracking_segments.cpp
@@ -1,53 +1 @@
-//PROBLEM STATEMENT- https://codeforces.com/problemset/problem/1843/E
 
-//SUBMISSION LINK- https://codeforces.com/problemset/submission/1843/356028549
-
-
-//APPROACH- Standard binary search on queries as they are monotonues (F F F T T TT)
-//TIME COMPLEXITY- O(nlogn)
-//SPACE COMPLEXITY- O(n)
-
-
-
-
-#include<bits/stdc++.h>
-using namespace std;
-
-bool ok(vector<pair<int,int>>&seg,vector<int>&q,int mid,int n){
-    vector<int>a(n,0);
-    for(int i=0;i<mid;i++)a[q[i]-1]=1;
-
-    vector<int>pre(n+1,0);
-    for(int i=0;i<n;i++)pre[i+1]=pre[i]+a[i];
-
-    for(auto &p:seg){
-        if(pre[p.second]-pre[p.first-1]>(p.second-p.first+1)/2)
-            return true;
-    }
-    return false;
-}
-
-void solve(){
-    int n,m;cin>>n>>m;
-    vector<pair<int,int>>seg(m);
-    for(int i=0;i<m;i++)cin>>seg[i].first>>seg[i].second;
-
-    int qn;cin>>qn;
-    vector<int>q(qn);
-    for(int i=0;i<qn;i++)cin>>q[i];
-
-    int l=1,r=qn,ans=-1;
-    while(l<=r){
-        int mid=(l+r)/2;
-        if(ok(seg,q,mid,n)){
-            ans=mid;
-            r=mid-1;
-        }else l=mid+1;
-    }
-    cout<<ans<<"\n";
-}
-
-int main(){
-    int t;cin>>t;
-    while(t--)solve();
-}

From d87916eeede38dfdc72ae9461dd00dd89cd2912e Mon Sep 17 00:00:00 2001
From: suzzzal <kshatrisujal@gmail.com>
Date: Thu, 1 Jan 2026 10:58:35 +0530
Subject: [PATCH 7/8] Delete
 algos/range_queries/PrefixSum/soln/Sujal/b_reverse_sort.cpp

---
 algos/range_queries/PrefixSum/soln/Sujal/b_reverse_sort.cpp | 1 -
 1 file changed, 1 deletion(-)
 delete mode 100644 algos/range_queries/PrefixSum/soln/Sujal/b_reverse_sort.cpp

diff --git a/algos/range_queries/PrefixSum/soln/Sujal/b_reverse_sort.cpp b/algos/range_queries/PrefixSum/soln/Sujal/b_reverse_sort.cpp
deleted file mode 100644
index 8b13789..0000000
--- a/algos/range_queries/PrefixSum/soln/Sujal/b_reverse_sort.cpp
+++ /dev/null
@@ -1 +0,0 @@
-

From a534dd32184d21590a8f2ff024cc00f7710f12f1 Mon Sep 17 00:00:00 2001
From: suzzzal <kshatrisujal@gmail.com>
Date: Thu, 1 Jan 2026 10:58:45 +0530
Subject: [PATCH 8/8] Delete
 algos/range_queries/PrefixSum/soln/Sujal/tracking_segments.cpp

---
 algos/range_queries/PrefixSum/soln/Sujal/tracking_segments.cpp | 1 -
 1 file changed, 1 deletion(-)
 delete mode 100644 algos/range_queries/PrefixSum/soln/Sujal/tracking_segments.cpp

diff --git a/algos/range_queries/PrefixSum/soln/Sujal/tracking_segments.cpp b/algos/range_queries/PrefixSum/soln/Sujal/tracking_segments.cpp
deleted file mode 100644
index 8b13789..0000000
--- a/algos/range_queries/PrefixSum/soln/Sujal/tracking_segments.cpp
+++ /dev/null
@@ -1 +0,0 @@
-