DataStructureAndAlgorithm/2023206/main.cpp

#include <stdio.h>
#define TREE_SIZE 50000
struct TreeNode {
    int val;
    int left;
    int right;
};

TreeNode tree[TREE_SIZE] = {0};
int num_in_tree[TREE_SIZE] = {0};
int num_in_tree_head = 0, num_in_tree_tail = 0;
int tree_root = -1;
int new_tree_node = 0;
int M, K, H;
long long total = 0;

int enqueue(int num) {
    num_in_tree[num_in_tree_tail] = num;
    num_in_tree_tail = (num_in_tree_tail + 1) % TREE_SIZE;
    return 0;
}

int dequeue() {
    int ans = num_in_tree[num_in_tree_head];
    num_in_tree_head = (num_in_tree_head + 1) % TREE_SIZE;
    return ans;
}

int insert_node(int num, int pos) {
    if (pos < 0) {
        // The tree_root is -1!
        tree[new_tree_node] = TreeNode{num, -1, -1};
        tree_root = new_tree_node;
        new_tree_node = (new_tree_node + 1) % TREE_SIZE;
        return 0;
    }
    // tree[pos].size++;
    if (tree[pos].val > num) {
        if (tree[pos].left < 0) {
            tree[pos].left = new_tree_node;
            tree[new_tree_node] = TreeNode{num, -1, -1};
            new_tree_node = (new_tree_node + 1) % TREE_SIZE;
            return 0;
        }
        else {
            insert_node(num, tree[pos].left);
            return 0;
        }
    }
    else {
        if (tree[pos].right < 0) {
            tree[pos].right = new_tree_node;
            tree[new_tree_node] = TreeNode{num, -1, -1};
            new_tree_node = (new_tree_node + 1) % TREE_SIZE;
            return 0;
        }
        else {
            insert_node(num, tree[pos].right);
            return 0;
        }
    }
}

int delete_node(int num, int pos) {
    if (pos < 0) {
        return -1;
    }

    if (tree[pos].val < num) {
        // tree[pos].size--;
        tree[pos].right = delete_node(num, tree[pos].right);
        return pos;
    }

    if (tree[pos].val > num) {
        // tree[pos].size--;
        tree[pos].left = delete_node(num, tree[pos].left);
        return pos;
    }

    // If reached here, tree[pos].val == num, so we are going to delete tree[pos]
    if (tree[pos].left < 0) {
        // The case when left is null, right is something
        // and also the case when both left and right is null
        return tree[pos].right;
    }

    if (tree[pos].right < 0) {
        // The case when left is something while right is null
        return tree[pos].left;
    }

    // Here, we deal with the case that both children exist.
    int parent = pos;
    int child = tree[parent].right;
    // tree[parent].size--;
    while (tree[child].left >= 0) {
        parent = child;
        child = tree[child].left;
        // tree[parent].size--;
    }

    if (parent == pos) {
        tree[parent].right = tree[child].right;
    }
    else {
        tree[parent].left = tree[child].right;
    }

    tree[pos].val = tree[child].val;
    return pos;
}

int traverse(int pos) {
    // printf("%d %d(", tree[pos].val, tree[pos].size);
    // printf("%d(", tree[pos].val);
    // if (tree[pos].left >= 0) {
    //     printf("l%d:", tree[pos].val);
    //     traverse(tree[pos].left);
    // }
    // if (tree[pos].right >= 0) {
    //     printf("r%d:", tree[pos].val);
    //     traverse(tree[pos].right);
    // }
    // printf(")");
    if (pos < 0) {
        return 0;
    }
    traverse(tree[pos].left);
    printf("%d ", tree[pos].val);
    traverse(tree[pos].right);
    return 0;
}

int get_size(int pos) {
    if (pos < 0) {
        return 0;
    }
    return 1 + get_size(tree[pos].left) + get_size(tree[pos].right);
}

int count_less_than(long long target, int pos) {
    if (pos < 0) {
        return 0;
    }

    if (tree[pos].val < target) {
        // if (tree[pos].left < 0) {
        //     return 1 + count_less_than(target, tree[pos].right);
        // }
        // return tree[tree[pos].left].size + 1 + count_less_than(target, tree[pos].right);
        return get_size(tree[pos].left) + 1 + count_less_than(target, tree[pos].right);
    }
    if (tree[pos].val > target) {
        return count_less_than(target, tree[pos].left);
    }

    // tree[pos].val == target

    // if (tree[pos].left < 0) {
    //     return 1;
    // }
    return 1 + get_size(tree[pos].left);
}

int main() {
    scanf("%d %d %d", &M, &K, &H);
    int num = 0;

    for (int i = 0; i < M; i++) {
        scanf("%d", &num);

        // traverse(tree_root);
        // printf("\n");
        // printf("num: %d, %d %d\n\n", num, count_less_than(num + H, tree_root),
        // if (i) {
        //     total += count_less_than(num + H, tree_root) - count_less_than(num - H - 1,
        //     tree_root);
        // }

        total += count_less_than(((long long)num) + H, tree_root) - count_less_than(num - H - 1, tree_root);
        if (i >= K) {
            tree_root = delete_node(dequeue(), tree_root);
        }
        enqueue(num);
        insert_node(num, tree_root);
    }

    printf("%lld\n", total);

    // int count = 0;
    // int num = 0;
    // scanf("%d", &count);
    // for (int i = 0; i < count; i++) {
    //     scanf("%d", &num);
    //     insert_node(num, tree_root);
    // }

    // for (int i = 0; i < count; i++) {
    //     printf("%d ", count_less_than(i, tree_root));
    // }

    return 0;
}