Add Segment Tree implementation

Search/SegmentTree

@@ -0,0 +1,76 @@
+#include <bits/stdc++.h>
+
+typedef long long ll;
+
+#define pb push_back
+#define MS(x,y) memset((x),(y),sizeof((x)))
+#define mn 1000000
+
+using namespace std;
+
+int tree[1000001];
+
+void update (int pos, int value, int interval_index, int interval_left, int interval_right) {
+    if (interval_left > pos || interval_right < pos || interval_left > interval_right) return;
+
+    if (interval_left == interval_right) {
+        if (interval_left == pos) tree[interval_index] = value;
+
+        return;
+    }
+
+    int mid = (interval_left + interval_right) / 2;
+    update(pos, value, 2*interval_index, interval_left, mid);
+    update(pos, value, 2*interval_index+1, mid+1, interval_right);
+
+    tree[interval_index] = tree[2*interval_index] + tree[2*interval_index+1];
+}
+
+int query (int from, int to, int interval_index, int interval_left, int interval_right) {
+    if (interval_left > to || interval_right < from || interval_left > interval_right) return 0;
+
+    if (from <= interval_left && interval_right <= to) return tree[interval_index];
+
+    int mid = (interval_left + interval_right) / 2;
+
+    return query(from, to, 2*interval_index, interval_left, mid) + query(from, to, 2*interval_index+1, mid+1, interval_right);
+}
+
+int main()
+{
+    MS(tree, 0);
+
+    int n;
+
+    cin>>n;
+
+    int niza[n];
+
+    for (int i = 0; i<n; i++) {
+        cin>>niza[i];
+
+        update(i, niza[i], 1, 0, n-1);
+    }
+
+    int m;
+
+    cin>>m;
+
+    for (int i = 0; i<m; i++) {
+        int a,b,c;
+
+        cin>>a>>b>>c;
+
+        if (a == 0) {
+            //change, c na pos b
+
+            update(b, c, 1, 0, n-1);
+        } else {
+            //query b to c
+
+            cout<<query(b, c, 1, 0, n-1)<<endl;
+        }
+    }
+
+    return 0;
+}