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Author: MathProgrammer

C Programs/C Programs - 3/Multiples of 3.cpp

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+#include <cstdio>
+
+const int MAX_SIZE = 1e5 + 3;
+
+int tree[3*MAX_SIZE][3];
+int lazy[3*MAX_SIZE] = {0};
+int element[MAX_SIZE] = {0};
+
+void swap(int &a, int &b, int &c)
+{
+    int temp_a = a, temp_b = b, temp_c = c;
+
+    c = temp_b;
+    b = temp_a;
+    a = temp_c;
+}
+
+void build(int node, int start, int end)
+{
+    if(start == end)
+    {
+        int mod = element[start]%3;
+        int mod_2 = (mod + 1)%3, mod_3 = (mod + 2)%3;
+
+        tree[node][mod] = 1;
+        tree[node][mod_2] = tree[node][mod_3] = 0;
+
+        return;
+    }
+
+    int mid = (start + end)/2;
+
+    build(2*node, start, mid);
+    build(2*node + 1, mid + 1, end);
+
+    for(int m = 0; m < 3; m++)
+        tree[node][m] = tree[2*node][m] + tree[2*node + 1][m];
+}
+
+void propagate(int node, int start, int end)
+{
+    int no_of_additions = lazy[node]%3;
+
+    if(no_of_additions == 1)
+    {
+        swap(tree[node][0], tree[node][1], tree[node][2]);
+    }
+    else if(no_of_additions == 2)
+    {
+        swap(tree[node][0], tree[node][2], tree[node][1]);
+    }
+
+    if(start != end)
+    {
+        lazy[2*node] = (lazy[2*node] + lazy[node])%3;
+        lazy[2*node + 1] = (lazy[2*node + 1] + lazy[node])%3;
+    }
+    lazy[node] = 0;
+}
+
+void update(int node, int start, int end, int query_start, int query_end)
+{
+    if(lazy[node])
+        propagate(node, start, end);
+
+    if(query_start > end || query_end < start)
+        return;
+
+    if(query_start <= start && end <= query_end)
+    {
+        swap(tree[node][0], tree[node][1], tree[node][2]);
+
+        if(start != end)
+        {
+            lazy[2*node]++;
+            lazy[2*node] %= 3;
+
+            lazy[2*node + 1]++;
+            lazy[2*node + 1] %= 3;
+        }
+        return;
+    }
+
+    int mid = (start + end)/2;
+
+    update(2*node, start, mid, query_start, query_end);
+    update(2*node + 1, mid + 1, end, query_start, query_end);
+
+    for(int m = 0; m < 3; m++)
+        tree[node][m] = tree[2*node][m] + tree[2*node + 1][m];
+}
+
+int query(int node, int start, int end, int query_start, int query_end)
+{
+    if(lazy[node])
+        propagate(node, start, end);
+
+    if(query_start > end || query_end < start)
+        return 0;
+
+    if(query_start <= start && end <= query_end)
+        return tree[node][0];
+
+    int mid = (start + end)/2;
+
+    int left_answer  = query(2*node, start, mid, query_start, query_end);
+    int right_answer = query(2*node + 1, mid + 1, end, query_start, query_end);
+
+    return (left_answer + right_answer);
+}
+
+int main()
+{
+    int no_of_elements;
+    scanf("%d", &no_of_elements);
+
+    build(1, 1, no_of_elements);
+
+    int no_of_queries;
+    scanf("%d", &no_of_queries);
+
+    while(no_of_queries--)
+    {
+        int type, left, right;
+        scanf("%d %d %d", &type, &left, &right);
+
+        left++, right++;
+
+        if(type == 0)
+        {
+            update(1, 1, no_of_elements, left, right);
+        }
+        else if(type == 1)
+        {
+            int answer = query(1, 1, no_of_elements, left, right);
+            printf("%d\n", answer);
+        }
+    }
+
+    return 0;
+}