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c++ - 如何在帕斯卡三角形中积分一行？

问题描述

我有一个最大行数为 5 的帕斯卡三角形。假设我想找到第四行的积分。如何访问帕斯卡三角形中的第四行。More precisely I want to know how to access a row in the pascal's triangle by entering the number n of the row

代码 

#include <iostream>

using namespace std;

int main(){

    int a1, a2, a3, a4, a5, pascal, columns;
    const int rows = 5;

    int **array = new int *[rows]; //generating array
    for(int i = 0; i <= rows; i++)
    array[i] = new int [columns];

    for (int i = 0; i <= rows; i++){  //loop for te pascal's triangle
        for (int j = 0; j <= i; j++){
            if(j == 0 || i == 0){
                pascal = 1;  //first element of pascal's triangle
            }
            else{
                pascal = pascal *(i - j + 1) / j; //pascal's triangle formula
            }
            cout << "  " << pascal; // printing pascals triangle
         }
         cout << "\n";
    }
    cout << "enter which row to integrate: ";
    // here I want to directly access a row rather that entering the elements of the row 
    cin >> a1;
    cin >> a2;
    cin >> a3;
    cin >> a4;
    cin >> a5;

 }

1
1 1
1 2 1
1 3 3 1 ------> 喜欢n = 4我想整合这一行的元素
1 4 6 4 1

答案应该是for 1,3,3,1 = 0, 1, 1.5, 1, 0.25

标签： c++arraysc++11visual-c++multidimensional-array

解决方案

你应该首先用元素填充数组，然后你可以像这样访问它们（编辑：确保初始化列变量，我将它设置为 5）

#include <iostream>

using namespace std;

int main() {

    int row_nb, pascal, columns = 5; //Initialized columns with columns = 5 
    const int rows = 5;

    int **array = new int *[rows]; //generating array
    for (int i = 0; i <= rows; i++)
        array[i] = new int[columns];

    for (int i = 0; i <= rows; i++) {  //loop for te pascal's triangle
        for (int j = 0; j <= i; j++) {
            if (j == 0 || i == 0) {
                pascal = 1;  //first element of pascal's triangle
            }
            else {
                pascal = pascal *(i - j + 1) / j; //pascal's triangle formula
            }
            array[i][j] = pascal; //fill the array
            cout << "  " << pascal; // printing pascals triangle
        }
        cout << "\n";
    }
    cout << "enter which row to intergrate: ";
    // here I want to directly access a row rather that entering the elements of the row 
    cin >> row_nb; //input the row you want to access

    for (int i = 0; i <= row_nb; i++) { //access the elements in this row in the array
    cout << array[row_nb][i] << " ";
}
    return 0; // add the return statement since the return type of the main function is int
}

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