第4讲数组_C/C++/C#

737. 数组替换

#include 
#include 

using namespace std;

int main()
{
    int a[10];
    for (int i = 0; i < 10; i ++ )
    {
        cin >> a[i];
        if (a[i] <= 0) a[i] = 1;
    }
    
    for (int i = 0; i < 10; i ++ )
        printf("X[%d] = %dn", i, a[i]);
    
    return 0;
}

738. 数组填充

#include 
#include 

using namespace std;

int main()
{
    int a[10];
    cin >> a[0];
    
    for (int i = 1; i < 10; i ++ ) a[i] = a[i - 1] * 2;
        
    for (int i = 0; i < 10; i ++ ) 
        printf("N[%d] = %dn", i, a[i]);
    
    return 0;
}

739. 数组选择

#include 
#include 

using namespace std;

int main()
{
    double a[100];
    for (int i = 0; i < 100; i ++ ) cin >> a[i];
    
    for (int i = 0; i < 100; i ++ ) 
        if (a[i] <= 10)
            printf("A[%d] = %.1lfn", i, a[i]);
    
    return 0;
}

740. 数组变换

#include 
#include 
#include 

using namespace std;

int main()
{
    int a[20];
    
    for (int i = 0; i < 20; i ++ ) cin >> a[i];
    
    reverse(a, a + 20);
    
    for (int i = 0; i < 20; i ++ ) printf("N[%d] = %dn", i, a[i]);
    
    return 0;
}

741. 斐波那契数列

#include 
#include 

using namespace std;

int main()
{
    long long t ,a[61];
    a[0] = 0, a[1] = 1;
    for (int i = 2; i < 61; i ++ ) a[i] = a[i - 1] + a[i - 2];
    
    cin >> t;
    while (t -- )
    {
        int n;
        cin >> n;
        printf("Fib(%d) = %lldn", n, a[n]);
    }
    
    return 0;
}

742. 最小数和它的位置

#include 
#include 

using namespace std;

int main()
{
    int a[1001];
    int n, pos = 0;
    
    cin >> n;
    cin >> a[0];
    for (int i = 1; i < n; i ++ )
    {
        cin >> a[i];
        if (a[i] < a[pos]) pos = i;
    }
    
    cout << "Minimum value: " << a[pos] << endl;
    cout << "Position: " << pos << endl;
    
    return 0;
}

743. 数组中的行

#include 
#include 

using namespace std;

int main()
{
    double m[12][12];
    int l;
    char t;
    
    cin >> l >> t;
    for (int i = 0; i < 12; i ++ )
        for (int j = 0; j < 12; j ++ )
            cin >> m[i][j];
    
    double sum = 0;
    for (int j = 0; j < 12; j ++ ) sum += m[l][j];
    
    if (t == 'S') printf("%.1lfn", sum);
    else printf("%.1lfn", sum / 12);
    
    return 0;
}

744. 数组中的列

#include 
#include 

using namespace std;

int main()
{
    double m[12][12];
    int c;
    char t;
    
    cin >> c >> t;
    for (int i = 0; i < 12; i ++ )
        for (int j = 0; j < 12; j ++ )
            cin >> m[i][j];
    
    double sum = 0;
    for (int i = 0; i < 12; i ++ ) sum += m[i][c];
    
    if (t == 'S') printf("%.1lfn", sum);
    else printf("%.1lfn", sum / 12);
    
    return 0;
}

745. 数组的右上半部分

#include 
#include 

using namespace std;

int main()
{
    double m[12][12];
    char t;
    
    cin >> t;
    for (int i = 0; i < 12; i ++ )
        for (int j = 0; j < 12; j ++ )
            cin >> m[i][j];
    
    double sum = 0;
    int cnt = 0;
    for (int i = 0; i < 11; i ++ )
        for (int j = i + 1; j < 12; j ++ , cnt ++ )
            sum += m[i][j];
    
    if (t == 'S') printf("%.1lfn", sum);
    else printf("%.1lfn", sum / cnt);
    
    return 0;
}

746. 数组的左下半部分

#include 
#include 

using namespace std;

int main()
{
    double m[12][12];
    char t;
    
    cin >> t;
    for (int i = 0; i < 12; i ++ )
        for (int j = 0; j < 12; j ++ )
            cin >> m[i][j];
    
    double sum = 0;
    int cnt = 0;
    for (int i = 1; i < 12; i ++ )
        for (int j = 0; j < i; j ++ , cnt ++ )
            sum += m[i][j];
    
    if (t == 'S') printf("%.1lfn", sum);
    else printf("%.1lfn", sum / cnt);
    
    return 0;
}

747. 数组的左上半部分

#include 
#include 

using namespace std;

int main()
{
    double m[12][12];
    char t;
    
    cin >> t;
    for (int i = 0; i < 12; i ++ )
        for (int j = 0; j < 12; j ++ )
            cin >> m[i][j];
    
    double sum = 0;
    int cnt = 0;
    for (int i = 0; i < 11; i ++ )
        for (int j = 0; j < 11 - i; j ++ , cnt ++ )
            sum += m[i][j];
    
    if (t == 'S') printf("%.1lfn", sum);
    else printf("%.1lfn", sum / cnt);
    
    return 0;
}

748. 数组的右下半部分

#include 
#include 

using namespace std;

int main()
{
    double m[12][12];
    char t;
    
    cin >> t;
    for (int i = 0; i < 12; i ++ )
        for (int j = 0; j < 12; j ++ )
            cin >> m[i][j];
    
    double sum = 0;
    int cnt = 0;
    for (int i = 1; i < 12; i ++ )
        for (int j = 12 - i; j < 12; j ++ , cnt ++ )
            sum += m[i][j];
    
    if (t == 'S') printf("%.1lfn", sum);
    else printf("%.1lfn", sum / cnt);
    
    return 0;
}

749. 数组的上方区域

#include 
#include 

using namespace std;

int main()
{
    double m[12][12];
    char t;
    
    cin >> t;
    for (int i = 0; i < 12; i ++ )
        for (int j = 0; j < 12; j ++ )
            cin >> m[i][j];
    
    double sum = 0;
    int cnt = 0;
    for (int i = 0; i < 5; i ++ )
        for (int j = i + 1; j < 11 - i; j ++ , cnt ++ )
            sum += m[i][j];
    
    if (t == 'S') printf("%.1lfn", sum);
    else printf("%.1lfn", sum / cnt);
    
    return 0;
}

750. 数组的下方区域

#include 
#include 

using namespace std;

int main()
{
    double m[12][12];
    char t;
    
    cin >> t;
    for (int i = 0; i < 12; i ++ )
        for (int j = 0; j < 12; j ++ )
            cin >> m[i][j];
    
    double sum = 0;
    int cnt = 0;
    for (int i = 7; i < 12; i ++ )
        for (int j = 12 - i; j < i; j ++ , cnt ++ )
            sum += m[i][j];
    
    if (t == 'S') printf("%.1lfn", sum);
    else printf("%.1lfn", sum / cnt);
    
    return 0;
}

751. 数组的左方区域

#include 
#include 

using namespace std;

int main()
{
    double m[12][12];
    char t;
    
    cin >> t;
    for (int i = 0; i < 12; i ++ )
        for (int j = 0; j < 12; j ++ )
            cin >> m[i][j];
    
    double sum = 0;
    int cnt = 0;
    for (int i = 1; i < 11; i ++ )
        for (int j = 0; j < min(i, 11 - i); j ++ , cnt ++ )
            sum += m[i][j];
    
    if (t == 'S') printf("%.1lfn", sum);
    else printf("%.1lfn", sum / cnt);
    
    return 0;
}

752. 数组的右方区域

#include 
#include 

using namespace std;

int main()
{
    double m[12][12];
    char t;
    
    cin >> t;
    for (int i = 0; i < 12; i ++ )
        for (int j = 0; j < 12; j ++ )
            cin >> m[i][j];
    
    double sum = 0;
    int cnt = 0;
    for (int i = 1; i < 11; i ++ )
        for (int j = max(12 - i, i + 1); j < 12; j ++ , cnt ++ )
            sum += m[i][j];
    
    if (t == 'S') printf("%.1lfn", sum);
    else printf("%.1lfn", sum / cnt);
    
    return 0;
}

753. 平方矩阵 I

#include 
#include 

using namespace std;

int main()
{
    int n;
    while (cin >> n, n)
    {
        for (int i = 1; i <= n; i ++ )
        {
            for (int j = 1; j <= n; j ++ )
                cout << min(min(i, n - i + 1), min(j, n - j + 1)) << ' ';
            cout << endl;
        }
        cout << endl;
    }
    
    return 0;
}

754. 平方矩阵 II

#include 
#include 

using namespace std;

int main()
{
    int n;
    while (cin >> n, n)
    {
        for (int i = 1; i <= n; i ++ )
        {
            for (int j = 1; j <= n; j ++ )
                cout << abs(i - j) + 1 << ' ';
            cout << endl;
        }
        cout << endl;
    }
    
    return 0;
}

755. 平方矩阵 III

#include 
#include 
#include 

using namespace std;

int main()
{
    int n;
    while (cin >> n, n)
    {
        for (int i = 0; i < n; i ++ )
        {
            for (int j = 0; j < n; j ++ )
                cout << (int)pow(2, i + j) << ' ';
                //  cout << (1 << (i + j)) << ' ';
            cout << endl;
        }
        cout << endl;
    }
    
    return 0;
}

756. 蛇形矩阵

#include 
#include 

using namespace std;

const int N = 110;

int n, m;
int a[N][N];

int main()
{
    cin >> n >> m;
    
    int dx[] = {0, 1, 0, -1};
    int dy[] = {1, 0, -1, 0};
    int x = 0, y = 0, d = 0;
    
    for (int i = 1; i <= n * m; i ++ )
    {
        a[x][y] = i;
        
        int tx = x + dx[d];
        int ty = y + dy[d];
        if (tx >= n || tx < 0 || ty >= m || ty < 0 || a[tx][ty]) 
            d = (d + 1) % 4;
            
        x += dx[d];
        y += dy[d];
    }
    
    for (int i = 0; i < n; i ++ )
    {
        for (int j = 0; j < m; j ++ )
            cout << a[i][j] << ' ';
        cout << endl;
    }
    
    return 0;
}

其他知识点

一维数组

数组定义

int a[100];

数组初始化

int a[3] = {0, 1, 2};
int b[]  = {0, 1, 2};    // 自动分配大小
int c[4] = {1};         // 长度为 5，没有给出初始值默认为 0
int d[4] = {0};         // 长度为 4，初始值全为 0

// 全局变量	堆区	初始值随机	空间较大
// 局部变量	栈区	初始值为零	空间较小

多维数组

数组定义

int a[3][4];

数组初始化

int a[3][3] = {
    {1, 2, 3}, 
    {4, 5, 6},
    {7, 8, 9}
};

memset、memcpy

#include 
#include 

using namespace std;

int main()
{
    int a[10];
    memset(a, 0, sizeof(a));	// 以字节为单位初始化 （0 / -1）
    memcpy(b, a, sizeof(b));	// 将 a 复制到 b
    return 0;
}

浮点数比较

const double eps = 1e-6;

if (fabs(a - b) < eps) puts("相等");
else
{
    if (a > b) puts("a > b");
    else puts("a < b");
}

第4讲 数组

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第4讲数组