547. Friend Circles

There are N students in a class. Some of them are friends, while some are not. Their friendship is transitive in nature. For example, if A is adirect friend of B, and B is a direct friend of C, then A is anindirect friend of C. And we defined a friend circle is a group of students who are direct or indirect friends.

Given a N*N matrix M representing the friend relationship between students in the class. If M[i][j] = 1, then the i_th and j_th students aredirect friends with each other, otherwise not. And you have to output the total number of friend circles among all the students.

Example 1:

Input: [[1,1,0], [1,1,0], [0,0,1]]Output: 2Explanation:The 0th and 1st students are direct friends, so they are in a friend circle. The 2nd student himself is in a friend circle. So return 2.

Example 2:

Input: [[1,1,0], [1,1,1], [0,1,1]]Output: 1Explanation:The 0th and 1st students are direct friends, the 1st and 2nd students are direct friends, so the 0th and 2nd students are indirect friends. All of them are in the same friend circle, so return 1.

Note:

1. N is in range [1,200].
2. M[i][i] = 1 for all students.
3. If M[i][j] = 1, then M[j][i] = 1.

int findCircleNum(int** M, int MRowSize, int MColSize) {
   int i;
   int count=0;
   bool flag[200]={false};
   for(i=0;i<MRowSize;i++){
       if(flag[i]==true) continue;
       dfs(M,i,MRowSize,MColSize,flag);
       count++;
   }
    return count;
}

void dfs(int** M,int pos, int MRowSize, int MColSize,bool* flag)
{
    int i;
    flag[pos]=true;
    for(i=0;i<MColSize;i++){
        if(M[pos][i]==0 || flag[i]==true) continue;
        dfs(M,i,MRowSize,MColSize,flag);
    }
}