从所有顶点的给定度数构造一个图
这是一个 C++ 程序，用于为给定的固定度数序列生成图形。该算法为给定的度数序列生成一个无向图。它不包括自边和多重边。
例子：
Input : degrees[] = {2, 2, 1, 1}
Output : (0) (1) (2) (3)
(0) 0 1 1 0
(1) 1 0 0 1
(2) 1 0 0 0
(3) 0 1 0 0
Explanation : We are given that there
are four vertices with degree of vertex
0 as 2, degree of vertex 1 as 2, degree
of vertex 2 as 1 and degree of vertex 3
as 1. Following is graph that follows
given conditions.
(0)----------(1)
| |
| |
| |
(2) (3) 方法 ：
1- 输入顶点数及其对应的度数。
2- 声明邻接矩阵 mat[ ][ ] 来存储图形。
3- 要创建图形，请创建第一个循环以连接每个顶点“i”。
4-第二个嵌套循环将顶点“i”连接到它旁边的每个有效顶点“j”。
5-如果顶点“i”和“j”的度数大于零，则连接它们。
6-打印邻接矩阵。
基于上面的解释，下面是实现：
C++
// C++ program to generate a graph for a
// given fixed degrees
#include
using namespace std;
// A function to print the adjacency matrix.
void printMat(int degseq[], int n)
{
// n is number of vertices
int mat[n][n];
memset(mat, 0, sizeof(mat));
for (int i = 0; i < n; i++) {
for (int j = i + 1; j < n; j++) {
// For each pair of vertex decrement
// the degree of both vertex.
if (degseq[i] > 0 && degseq[j] > 0) {
degseq[i]--;
degseq[j]--;
mat[i][j] = 1;
mat[j][i] = 1;
}
}
}
// Print the result in specified format
cout << "\n"
<< setw(3) << " ";
for (int i = 0; i < n; i++)
cout << setw(3) << "(" << i << ")";
cout << "\n\n";
for (int i = 0; i < n; i++) {
cout << setw(4) << "(" << i << ")";
for (int j = 0; j < n; j++)
cout << setw(5) << mat[i][j];
cout << "\n";
}
}
// driver program to test above function
int main()
{
int degseq[] = { 2, 2, 1, 1, 1 };
int n = sizeof(degseq) / sizeof(degseq[0]);
printMat(degseq, n);
return 0;
} Java
// Java program to generate a graph for a
// given fixed degrees
import java.util.*;
class GFG
{
// A function to print the adjacency matrix.
static void printMat(int degseq[], int n)
{
// n is number of vertices
int [][]mat = new int[n][n];
for (int i = 0; i < n; i++)
{
for (int j = i + 1; j < n; j++)
{
// For each pair of vertex decrement
// the degree of both vertex.
if (degseq[i] > 0 && degseq[j] > 0)
{
degseq[i]--;
degseq[j]--;
mat[i][j] = 1;
mat[j][i] = 1;
}
}
}
// Print the result in specified format
System.out.print("\n" + setw(3) + " ");
for (int i = 0; i < n; i++)
System.out.print(setw(3) + "(" + i + ")");
System.out.print("\n\n");
for (int i = 0; i < n; i++)
{
System.out.print(setw(4) + "(" + i + ")");
for (int j = 0; j < n; j++)
System.out.print(setw(5) + mat[i][j]);
System.out.print("\n");
}
}
static String setw(int n)
{
String space = "";
while(n-- > 0)
space += " ";
return space;
}
// Driver Code
public static void main(String[] args)
{
int degseq[] = { 2, 2, 1, 1, 1 };
int n = degseq.length;
printMat(degseq, n);
}
}
// This code is contributed by 29AjayKumarPython3
# Python3 program to generate a graph
# for a given fixed degrees
# A function to print the adjacency matrix.
def printMat(degseq, n):
# n is number of vertices
mat = [[0] * n for i in range(n)]
for i in range(n):
for j in range(i + 1, n):
# For each pair of vertex decrement
# the degree of both vertex.
if (degseq[i] > 0 and degseq[j] > 0):
degseq[i] -= 1
degseq[j] -= 1
mat[i][j] = 1
mat[j][i] = 1
# Print the result in specified form
print(" ", end = " ")
for i in range(n):
print(" ", "(", i, ")", end = "")
print()
print()
for i in range(n):
print(" ", "(", i, ")", end = "")
for j in range(n):
print(" ", mat[i][j], end = "")
print()
# Driver Code
if __name__ == '__main__':
degseq = [2, 2, 1, 1, 1]
n = len(degseq)
printMat(degseq, n)
# This code is contributed by PranchalKC#
// C# program to generate a graph for a
// given fixed degrees
using System;
class GFG
{
// A function to print the adjacency matrix.
static void printMat(int []degseq, int n)
{
// n is number of vertices
int [,]mat = new int[n, n];
for (int i = 0; i < n; i++)
{
for (int j = i + 1; j < n; j++)
{
// For each pair of vertex decrement
// the degree of both vertex.
if (degseq[i] > 0 && degseq[j] > 0)
{
degseq[i]--;
degseq[j]--;
mat[i, j] = 1;
mat[j, i] = 1;
}
}
}
// Print the result in specified format
Console.Write("\n" + setw(3) + " ");
for (int i = 0; i < n; i++)
Console.Write(setw(3) + "(" + i + ")");
Console.Write("\n\n");
for (int i = 0; i < n; i++)
{
Console.Write(setw(4) + "(" + i + ")");
for (int j = 0; j < n; j++)
Console.Write(setw(5) + mat[i, j]);
Console.Write("\n");
}
}
static String setw(int n)
{
String space = "";
while(n-- > 0)
space += " ";
return space;
}
// Driver Code
public static void Main(String[] args)
{
int []degseq = { 2, 2, 1, 1, 1 };
int n = degseq.Length;
printMat(degseq, n);
}
}
// This code is contributed by Princi SinghJavascript
输出：
(0) (1) (2) (3) (4)
(0) 0 1 1 0 0
(1) 1 0 0 1 0
(2) 1 0 0 0 0
(3) 0 1 0 0 0
(4) 0 0 0 0 0时间复杂度： O(v*v)。