LeetCode_ 118. Yanghui triangle_ Dynamic programming_ Int * * learning

Given a nonnegative integer numRows, Generate 「 Yang hui triangle 」 Before numRows That's ok .

stay 「 Yang hui triangle 」 in , Each number is the sum of the numbers at the top left and right of it .

Example 1:
Input : numRows = 5
Output : [[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1]]

Example 2:
Input : numRows = 1
Output : [[1]]

source ： Power button （LeetCode）
link ：https://leetcode-cn.com/problems/pascals-triangle
Copyright belongs to the network . For commercial reprint, please contact the official authority , Non-commercial reprint please indicate the source .

dp[i][j] = dp[i - 1][j] + dp[i - 1][j - 1];

Use a two-dimensional array ：
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Link to the original text ：https://blog.csdn.net/lalala_dxf/article/details/120106430

// Yang hui triangle 
#include<stdio.h>
#define N 10
int main(void)
{
    
	int i, j, a[N][N];

	// Make the numbers on both sides equal 1
	for (i = 0; i < N; i++)
	{
    
		a[i][0] = a[i][i] = 1;
	}

	// Except for the numbers on both sides, they are equal to the sum of the above two terms 
	for (i = 2; i < N; i++)
	{
    
		for (j = 1; j < i; j++)
		{
    
			a[i][j] = a[i - 1][j - 1] + a[i - 1][j];
		}
	}

	// Control output , The last number in each line has no spaces , There is a space between two adjacent numbers 
	for (i = 0; i < N; i++)
	{
    
		for (j = 0; j < i+1; j++)
		{
    
			if (j == i)
				printf("%d", a[i][j]);
			else
				printf("%d ", a[i][j]);
		}
		printf("\n");
	}
	return 0;
}

Li Kou official code ：

int** generate(int numRows, int* returnSize, int** returnColumnSizes) {
    
    int** ret = malloc(sizeof(int*) * numRows);
    *returnSize = numRows;
    *returnColumnSizes = malloc(sizeof(int) * numRows);
    for (int i = 0; i < numRows; ++i) {
    
        ret[i] = malloc(sizeof(int) * (i + 1));
        (*returnColumnSizes)[i] = i + 1;
        ret[i][0] = ret[i][i] = 1;
        for (int j = 1; j < i; ++j) {
    
            ret[i][j] = ret[i - 1][j] + ret[i - 1][j - 1];
        }
    }
    return ret;
}

 author ：LeetCode-Solution
 link ：https://leetcode-cn.com/problems/pascals-triangle/solution/yang-hui-san-jiao-by-leetcode-solution-lew9/
 source ： Power button （LeetCode）
 The copyright belongs to the author . Commercial reprint please contact the author for authorization , Non-commercial reprint please indicate the source .

Understanding supplement ：

int ** The understanding of the ：https://yian.me/blog/what-is/pointer-to-pointer-in-c-programing-language.html?utm_source=tuicool&utm_medium=referral
The type of content pointed to by the pointer is different , A pointer to a int Type a point int * type .

int  i    integer 
int*  pi  Is a pointer to an integer variable 【 What is kept is  int  Variable of type  i  The address of 】
int**  ppi  Point to   A pointer to an integer variable   The pointer 【 What is kept is  int*  Variable of type  pi  The address of 】