add segment tree various implementations

data-structures/segtreefirstabove.cpp

@@ -0,0 +1,110 @@
+/*
+#pragma GCC target ("avx2")
+#pragma GCC optimize ("Ofast")
+#pragma GCC optimize ("unroll-loops")
+*/
+#include "bits/stdc++.h"
+ 
+#define iosb ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0)
+#define BIT(x) __builtin_popcount(x)
+#define all(x) x.begin() , x.end()
+#define F first
+#define S second
+#define pb push_back
+ 
+using namespace std ;
+ 
+typedef unsigned long long UL ;
+typedef long long L ;
+typedef string T ;
+typedef int I ;
+ 
+const I MaxN =      1e5+1 ;
+const I MOD =       1e9+7 ;
+const I inf =       2e9+7 ;
+const L INF = 2e18+7 ;
+
+L t[4*MaxN], mod[4*MaxN], a[MaxN], n, m ;
+
+void build(int v, int tl, int tr)
+{
+    if(tl == tr)
+    {
+        t[v] = a[tl] ;
+        return ;
+    }
+
+    int tm = (tl + tr) >> 1 ;
+    build(v*2, tl, tm) ;
+    build(v*2+1, tm+1, tr) ;
+    t[v] = max(t[v*2], t[v*2+1]) ;
+}
+
+void update(int v, int tl, int tr, int l, int x)
+{
+    if(tl == tr && tl == l)
+    {
+        t[v] = x ;
+        return ;
+    }
+    
+    if(tr < l || l < tl)
+        return ;
+
+    int tm = (tl + tr) >> 1 ;
+    update(v*2, tl, tm, l, x) ;
+    update(v*2+1, tm+1, tr, l, x) ;
+    t[v] = max(t[v*2], t[v*2+1]) ;
+}
+
+int above(int v, int tl, int tr, int l, int x)
+{
+    if(l > tr)
+        return -1 ;
+
+    if(tl == tr)
+    {
+        if(x > t[v])
+            return -1 ;
+        return tl ;
+    }
+
+    int tm = (tl + tr) >> 1 ;
+    if(t[v*2] >= x)
+    {
+        int ab = above(v*2, tl, tm, l, x) ;
+        if(ab == -1)
+            return above(v*2+1, tm+1, tr, l, x) ;
+    }
+    else
+        return above(v*2+1, tm+1, tr, l, x) ;
+}
+
+int32_t main(int argc, char *argv[])
+{
+    if(argc > 1)
+        freopen(argv[1], "r", stdin) ;
+    //freopen(".in" , "r" , stdin) ;
+    //freopen(".out" , "w" , stdout) ;
+    cin >> n >> m ;
+    for(int i = 0 ; i < n ; ++i)
+        cin >> a[i] ;
+
+    build(1, 0, n-1) ;
+
+    while(m--)
+    {
+        int type, l, x ;
+        cin >> type ;
+        if(type == 1)
+        {
+            cin >> l >> x ;
+            update(1, 0, n-1, l, x) ;
+        }
+        else
+        {
+            cin >> x >> l ;
+            cout << above(1, 0, n-1, l, x) << '\n' ;
+        }
+    }
+}

data-structures/segtreeinversions.cpp

@@ -0,0 +1,71 @@
+/*
+#pragma GCC target ("avx2")
+#pragma GCC optimize ("Ofast")
+#pragma GCC optimize ("unroll-loops")
+*/
+#include "bits/stdc++.h"
+ 
+#define iosb ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0)
+#define BIT(x) __builtin_popcount(x)
+#define all(x) x.begin() , x.end()
+#define F first
+#define S second
+#define pb push_back
+ 
+using namespace std ;
+ 
+typedef unsigned long long UL ;
+typedef long long L ;
+typedef string T ;
+typedef int I ;
+ 
+const I MaxN =      1e5+1 ;
+const I MOD =       1e9+7 ;
+const I inf =       2e9+7 ;
+const L INF = 2e18+7 ;
+
+L t[4*MaxN], mod[4*MaxN], a[MaxN], n, m ;
+
+void update(int v, int tl, int tr, int l, int x)
+{
+    if(tl == tr && tl == l)
+    {
+        t[v] = x ;
+        return ;
+    }
+    
+    if(tr < l || l < tl)
+        return ;
+
+    int tm = (tl + tr) >> 1 ;
+    update(v*2, tl, tm, l, x) ;
+    update(v*2+1, tm+1, tr, l, x) ;
+    t[v] = t[v*2] + t[v*2+1] ;
+}
+
+L get(int v, int tl, int tr, int l, int r)
+{
+    if(l <= tl && tr <= r)
+        return t[v] ;
+
+    if(l > tr || r < tl)
+        return 0 ;
+
+    int tm = (tl + tr) >> 1 ;
+    return get(v*2, tl, tm, l, r) + get(v*2+1, tm+1, tr, l, r) ;
+}
+
+int32_t main(int argc, char *argv[])
+{
+    if(argc > 1)
+        freopen(argv[1], "r", stdin) ;
+    //freopen(".in" , "r" , stdin) ;
+    //freopen(".out" , "w" , stdout) ;
+    cin >> n ;
+    for(int i = 0 ; i < n ; ++i)
+    {
+        cin >> a[i] ;
+        cout << get(1, 1, n, a[i], n) << ' ' ;
+        update(1, 1, n, a[i], 1) ;
+    }
+}