HDU 1530 maximum clique

The question ： Give an undirected graph , Find the knot number of the largest clique .

Answer key ： The biggest group
group ： If the picture is a group , Then the graph is undirected .
Great regiment ： Not a subset of other groups .
The biggest group ： The largest number of knots .

#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include<cstdio>
#include<string>
#include<cstring>
#include<algorithm>
#include<queue>
#include<stack>
#include<cmath>
#include<vector>
#include<fstream>
#include<set>
#include<map>
#include<sstream>
#include<iomanip>
#define ll long long
#define pii pair<int, int>
using namespace std;
/*  The biggest group  =  Make up a picture G The maximum number of independent sets of  ———> Maximum number of independent sets  =  Make up a picture G' The biggest group  */
// The largest group template 
#define N 102
int mx;// Maximum number of cliques ( To initialize to 0)
int x[N], tuan[N];
int can[N][N];//can[i] Indicates that the selected i A point must be in the largest clique and may be added to the node set of the largest clique 
int num[N];//num[i] Indicates by node i To the node n The number of knots of the largest group formed 
bool g[N][N];// Adjacency matrix ( from 1 Start )
int n;
bool dfs(int tot, int cnt) {
    
	int i, j, k;
	if (tot == 0) {
    
		if (cnt > mx) {
    
			mx = cnt;
			for (i = 0; i < mx; i++) {
    
				tuan[i] = x[i];
			}
			return true;
		}
		return false;
	}
	for (i = 0; i < tot; i++) {
    
		if (cnt + (tot - i) <= mx)return false;
		if (cnt + num[can[cnt][i]] <= mx)return false;
		k = 0;
		x[cnt] = can[cnt][i];
		for (j = i + 1; j < tot; j++) {
    
			if (g[can[cnt][i]][can[cnt][j]]) {
    
				can[cnt + 1][k++] = can[cnt][j];
			}
		}
		if (dfs(k, cnt + 1))return false;
	}
	return false;
}
void MaxTuan() {
    
	int i, j, k;
	mx = 1;
	for (i = n; i >= 1; i--) {
    
		k = 0;
		x[0] = i;
		for (j = i + 1; j <= n; j++) {
    
			if (g[i][j]) {
    
				can[1][k++] = j;
			}
		}
		dfs(k, 1);
		num[i] = mx;
	}
}
int main() {
    
	while (scanf("%d", &n) && n) {
    
		for (int i = 1; i <= n; i++) {
    
			for (int j = 1; j <= n; j++) {
    
				scanf("%d", &g[i][j]);
			}
		}
		mx = 0;
		MaxTuan();
		printf("%d\n", num[1]);
	}
	return 0;
}