求解for循环的应用

Question

Answer 1

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c++实现效果图：

#include <iostream>
using namespace std;
int main() {
int n, i, j;
cout << "Input a number:" << endl;
cin >> n;
i = n - 1;
j = 1;
while (i >= 0 && j <= 2 * n - 1)
{
    int w = i;
    int t = j;
    for (i = w; i > 0; i--)
        cout << ' ';
    for (j = 1; j <= 2 * t - 1; j++)
        cout << '*';
    for (i = w; i > 0; i--)
        cout << ' ';
    i = w;
    j = t;
    i--; j++;
    cout << endl;
}
i = 1;
j = n - 1;
while (i >= 0 && j >= 1)
{
    int w = i;
    int t = j;
    for (i = w; i > 0; i--)
        cout << ' ';
    for (j = 1; j <= 2 * t - 1; j++)
        cout << '*';
    for (i = w; i > 0; i--)
        cout << ' ';
    i = w;
    j = t;
    i++; j--;
    cout << endl;
    }
cout << endl;
return 0;
}