杨辉三角(数组)

Posted 2021-03-07 hujianglang

//杨辉三角(数组)
/*
* @Description: Given a non-negative integer numRows, generate the first numRows of Pascal‘s triangle.
 * Input: 5
 * Output:
 * [
 *      [1],
 *     [1,1],
 *    [1,2,1],
 *   [1,3,3,1],
 *  [1,4,6,4,1]
 * ]
*/
#include <stdlib.h>
#include <vector>
#include <iostream>
using namespace std;

vector<vector<int>> generate(int numRows){
    vector<vector<int>> pascalTriangle;
    for(int i = 0; i < numRows; i++){
       vector<int> v;
       if(i == 0){
           v.push_back(1);
       }
       else{
           v.push_back(1);
           for(int j=0; j < pascalTriangle[i-1].size()-1;j++){
               v.push_back(pascalTriangle[i-1][j] + pascalTriangle[i-1][j+1]);
           }
           v.push_back(1);
       }
       pascalTriangle.push_back(v);
    }
    return pascalTriangle;
}

void printTriangle(vector<vector<int>> pt){
    cout << "[" << endl;
    for(int i = 0;i<pt.size();i++){
        for(int space=(pt.size()-i-1);space>=0;space--){
            cout << " ";
        }
        for(int j = 0; j < pt[i].size(); j++){
            cout << pt[i][j];
            if(j<pt[i].size()-1){
                cout << ",";
            }
        }

        cout << "]";
        if(i<pt.size()-1){
            cout << ",";
        }
        cout << endl;
    }
    cout <<  "]" << endl;
}

int main(int argc, char**argv)
{
    int n = 3;
    if(argc > 1){
        n = atoi(argv[1]);
    }
    printTriangle(generate(n));
}