02二位数组算法

1.杨辉三角

算法思想：

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

代码：

#include
using namespace std;
const int N = 1e2 + 10;
int a[N][N];
int main() {
	int n; cin >> n;
	a[1][1] = a[2][1] = a[2][2] = 1;
	for (int i = 3; i <= n; i++) {
		for (int j = 1; j <= i; j++) {
			if (j == 1 || j == i) a[i][j] = 1;
			else a[i][j] = a[i - 1][j] + a[i - 1][j - 1];
		}
	}

	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= i; j++) {
			cout << a[i][j] << " ";
		}cout << endl;
	}
	return 0;
}

2.蛇形添数

算法思想：下左上右，自己多模拟几遍

#include 
#include 
const int N=1e4+10;
int nums[N][N],n,l,r,x;
using namespace std;
void text01(){
    cin>>n;//4
    l=1;
    r=n;
    while(x=l;j--){//左
            nums[r][j]=++x;
        }
        for(int i=r-1;i>=l;i--){//上
            nums[i][l]=++x;
        }
        for(int j=l+1;j<=r-1;j++){//右
            nums[l][j]=++x;
        }
        l++;
        r--;
    }
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            cout<

3.矩阵乘法

核心算法

A n m
B m k
最里层循环，假设是A的第一行*B的第一列,恰好遍历长度都是m所以最里层是m的循环
次里层循环，是k的循环
最外层循环，是n的循环

#include
using namespace std;
const int N = 1e2 + 10;
int a[N][N],b[N][N],c[N][N];
int main() {
	int n, m, k; cin >> n >> m >> k;

	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= m; j++) {
			cin >> a[i][j];
		}
	}

	for (int i = 1; i <= m; i++) {
		for (int j = 1; j <= k; j++) {
			cin >> b[i][j];
		}
	}

	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= k; j++) {
			for (int p = 1; p <= m; p++) {
				c[i][j] += a[i][p] * b[p][j];
			}
		}
	}
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= k; j++) {
			cout << c[i][j] << " ";
		}cout << endl;
	}


	return 0;
}