added persistent sement trees + ST on maps

Author: rachitiitr

Library/DS/persistent_segment_tree.cpp

@@ -0,0 +1,50 @@
+
+// query l to r range for the no of integers between x and y
+#include <iostream>
+using namespace std;
+int T = 1;
+const int N = 1e6;
+const int MX = N;
+struct node{
+	int l, r, cnt;	
+}t[100*MX];
+int root[N], a[N];
+int build(int lo, int hi){
+	int id = T++;
+	if(lo == hi) return id;
+	int  mid = (lo+hi)/2;
+	t[id].l = build(lo, mid);
+	t[id].r = build(mid+1, hi);
+	return id;
+}
+int update(int rt, int lo, int hi, int val){
+	int id = T++;
+	t[id] = t[rt]; t[id].cnt++;
+	if(lo == hi) return id;
+	int mid = (lo+hi)/2;
+	if(val <= mid) t[id].l = update(t[rt].l, lo, mid, val);
+	else t[id].r = update(t[rt].r, mid+1, hi, val);
+	return id;
+}
+int query(int rt, int lo, int hi, int x, int y){
+	if(x==lo and y==hi) return t[rt].cnt;
+	int mid = (lo+hi)/2;
+	if(y <= mid) return query(t[rt].l, lo, mid, x, y);
+	else if (x > mid) return query(t[rt].r, mid+1, hi, x, y);
+	return query(t[rt].l, lo, mid, x, mid)	+ query(t[rt].r, mid+1, hi, mid+1, y);
+}
+int main() {
+	int i, n, q;
+	cin >> n >> q;
+	for(i = 0; i < n; i++) cin >> a[i+1];
+	root[0] = build(0, MX);
+	for(i = 1; i <= n; i++){
+		root[i] = update(root[i-1], 0, MX, a[i]);
+	}
+	while(q--){
+		int l, r, x, y;
+		cin >> l >> r >> x >> y;
+		cout << query(root[r], 0, MX, x, y) - query(root[l-1], 0, MX, x, y) << endl;
+	}
+	return 0;
+}

Library/DS/segment_tree_on_map.cpp

@@ -0,0 +1,40 @@
+#include <bits/stdc++.h>
+using namespace std;
+const int N = 2e6;
+map<int, long long> my[N];
+void update(int st, int lo, int hi, int pos, int val){
+	my[st][val]++;
+	if(lo == hi){
+		return;
+	}
+	int l = 2*st, r = l+1, mid = (lo+hi)/2;
+	if(pos>mid) update(r, mid+1, hi, pos, val);
+	else update(l, lo, mid, pos, val);
+}
+long long query(int st, int lo, int hi, int x, int y, int val){
+	if(lo == x and hi == y){
+		return my[st][val];
+	}
+	int l = 2*st, r = l+1, mid = (lo+hi)/2;
+	if(x>mid) return query(r, mid+1, hi, x, y, val);
+	else if(y<=mid) return query(l, lo, mid, x, y, val);
+	return query(l ,lo , mid, x, mid, val) + query(r, mid+1, hi, mid+1, y, val);
+}
+
+int main() {
+	int n, i, q, k, l, t, r;
+	cin >> n >> q;
+	while(q--){
+		cin >> t >> l >> r;
+		if(t == 1){
+			//add l to a[r]
+			update(1, 0, n-1, r-1, l);
+		}
+		else{
+			//count of k from a[l] to a[r].
+			cin >> k;
+			cout << query(1, 0, n-1, l-1, r-1, k) << endl;
+		}
+	}
+	return 0;
+}