binarysearchc.cpp

#include <stdio.h>

int binary_search(int arr[], int l, int r, int x) {
    while (l <= r) {
        int m = l + (r - l) / 2;
        if (arr[m] == x)
            return m;
        if (arr[m] < x)
            l = m + 1;
        else
            r = m - 1;
    }
    return -1;
}

void merge(int arr[], int l, int m, int r) {
    int i, j, k;
    int n1 = m - l + 1;
    int n2 = r - m;

    int L[n1], R[n2];

    for (i = 0; i < n1; i++)
        L[i] = arr[l + i];
    for (j = 0; j < n2; j++)
        R[j] = arr[m + 1 + j];

    i = 0;
    j = 0;
    k = l;
    while (i < n1 && j < n2) {
        if (L[i] <= R[j]) {
            arr[k] = L[i];
            i++;
        }
        else {
            arr[k] = R[j];
            j++;
        }
        k++;
    }

    while (i < n1) {
        arr[k] = L[i];
        i++;
        k++;
    }

    while (j < n2) {
        arr[k] = R[j];
        j++;
        k++;
    }
}

void merge_sort(int arr[], int l, int r) {
    if (l < r) {
        int m = l + (r - l) / 2;

        merge_sort(arr, l, m);
        merge_sort(arr, m + 1, r);

        merge(arr, l, m, r);
    }
}

int main() {
    int n, q, m;
    scanf("%d", &n);
    int a[n];
    for (int i = 0; i < n; i++) {
        scanf("%d", &a[i]);
    }
    scanf("%d", &q);
    for (int i = 1; i <= q; i++) {
        scanf("%d", &m);
        int l = 0, r = n - 1;
        merge_sort(a, l, r);
        int ans = -1;
        while (l <= r) {
            int mid = (l + r) / 2;
            if (a[mid] <= m) {
                ans = mid;
                l = mid + 1;
            }
            else {
                r = mid - 1;
            }
        }
        printf("Case #%d: %d\n", i, ans + 1);
    }
    return 0;
}