图的m着色（回溯法）

////Description:图的m着色问题(回溯法)//#include <iostream>using namespace std;int n;//图的顶点个数int m;//可用颜色数int a[21][21];//程序中使用时从下标1开始;程序中用于存储图的邻接矩阵int x[20];//用于存储当前解static  long sum;//当前已找到的可m着色方案数bool ok(int k){for (int j = 1; j <= n; j++){if (a[k][j] && (x[j] == x[k]))return 0;}return 1;}void backtrack(int t){if (t>n){sum++;cout << "        第" << sum << "种解决方案为 ：\n";for (int i = 1; i <= n; i++){cout << x[i] << " ";}cout << endl;}else{for (int i = 1; i <= m; i++){x[t] = i;if (ok(t)){backtrack(t + 1);}x[t] = 0;}}}long mColoring(int mm){m = mm;sum = 0;backtrack(1);return sum;}void inputRenc(int  p[21][21]){for (int i = 1; i <= n; i++){for (int j = i + 1; j <= n; j++)  //**分析为什么如邻接矩阵中[1][1]为1？？？{cout << "请输图的邻接矩阵中[" << i << "][" << j << "]的值" << endl;cin >> p[i][j];p[j][i] = p[i][j];}cout << endl;}}void  outputRenc(int  p[21][21]){for (int i = 1; i <= n; i++){for (int j = 1; j <= n; j++){cout << p[i][j] << ' ';}cout << endl;}}void main(){cout << "\n\t==========图的m着色问题============\n";cout << "Please enter the number of points and colors :\n";cin >> n >> m;cout << "\n==========(输入)图的邻接矩阵\n";inputRenc(a);cout << "\n==========(输出)图的邻接矩阵\n";outputRenc(a);cout << "\n==========判断可着色性\n";mColoring(m);if (sum == 0)cout << "  无可行方案！" << endl;cout << "-------------------------------------------------------------------------------" << endl;cout << n << " 个顶点" << "按所给的邻接关系着 " << m << " 种颜色，总的着色方案有 " << sum << " 个\n";}