查找和排序

顺序查找

void main() {
    int arr[] = {23, 12, 45, 67, 87};
    // 查找的数
    int num = 67;
    int len = sizeof(arr) / sizeof(int);
    for (int i = 0; i < len; i++) {
        if (num == arr[i]) {
            printf("找到%d", arr[i]);
            break;
        }
        else {
            printf("没有找到%d", num);
        }
    }
}

二分查找或折半查找

void main() {
    // 数组是已经排好序的
    int arr[] = {1, 2, 3, 22, 29, 54, 59, 123};
    int len = sizeof(arr) / sizeof(int);
    int num = 29;
    int min = 0;
    int max = len - 1;

    while (min <= max) {
        int mid = (min + max) / 2;
        printf("%d\n", mid);
        if (arr[mid] < num) {
            min = mid + 1;
        }

        else if (arr[mid] > num) {
            max = mid - 1;
        }
        else {
            printf("%d", num);
            break;
        }
    }

}

冒泡排序

int main() {
    int arr[] = {3, 5, 2, 1, 4};
    int len = sizeof(arr) / sizeof(int);
    for (int j = 0; j < len - 1; j++) {
        for (int i = 0; i < len - j - 1; i++) {
            if (arr[i] > arr[i + 1]) {
                int temp = arr[i];
                arr[i] = arr[i + 1];
                arr[i + 1] = temp;
            }
        }
    }


    for (int i = 0;i < len; i++) {
        printf("%d", arr[i]);
    }
}

选择排序

int main() {
    int arr[] = {3, 8, 2, 1, 4};
    int len = sizeof(arr) / sizeof(int);
    for (int i = 0; i < len - 1; i++) {
        for (int j = i; j < len - 1; j++) {
            if (arr[i] > arr[j + 1]) {
                int temp = arr[j + 1];
                arr[j + 1] = arr[i];
                arr[i] = temp;
            }
        }
    }
    
    for (int i = 0; i < len; i++) {
        printf("%d", arr[i]);
    }
}