Triangle right angle (C)

Triangle right angle

---

#include<stdio.h>
#define N 10
int main()
{
	int i,j,a[N][N];
	for(i=0;i<N;i++)
		a[i][i]=a[i][0]=1;
		
	for(i=2;i<N;i++)
		for(j=1;j<i;j++)
			a[i][j]=a[i-1][j]+a[i-1][j-1];
	
	//输出		
	for(i=0;i<N;i++){
		for(j=0;j<=i;j++)
			printf("%-10d",a[i][j]);
		printf("\n");		
	}
	return 0;
 } 

1. The first column is 1
2. The row number is equal to the column number 1 is also
3. In addition: the one below is actually the sum of its two heads

Triangle right angles, stored in a two-dimensional array, its regularity

1
1	1
1	2	1
1	3	3	1
1	4	6	4	1

Corresponding to the index:

0,0
1,0	1,1
2,0	2,1	2,2
3,0	3,1	3,2	3,3
4,0	4,1	4,2	4,3	4,4

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If you still feel right angle Triangle myself some difficult, difficult to understand, you can look at the following simple for loop problems, to find the feeling

• Output symbol C
  is typically in the book, the subject is a stepping stone for loop

#include<stdio.h>
int main()
{
	printf("***\n");
	printf("*\n");
	printf("*\n");
	printf("***\n");
	return;
}

• Output nine-by-nine formulas
  understanding of the double for the cycle

#include<stdio.h>
int main()
{
	int i, j;
	for(i = 1; i < 10; i++){
		for(j = 1 ;j < 10; j++){
			printf("%d * %d = %-4d", i, j, i*j);
		}
	printf("\n");	
	}
	return 0;
 } 

• Print triangle with a left loop
  start loop for flexible use

#include<stdio.h>
int main()
{
	int i,n;
	for(i = 1; i <= 7; i += 2){
		for(n = 1; n <= i; n++){
			printf("* ");
		} 
		printf("\n");
	}
	for(i = 5; i >= 1; i -= 2){
		for(n = 1; n <= i; n++){
			printf("* ");
		} 
		printf("\n");
	}
	return 0;
 }