亚马逊经典面试题实例详解

/* 
Q1. 
Map 
[ 
0 0 0 0 0 0 0 0 
0 1 0 0 0 0 0 0 
0 1 1 0 0 0 0 0 
0 0 0 0 0 0 1 0 
0 0 0 0 0 1 0 0 
0 0 0 0 0 0 0 0 
] 
*/

#include<iostream>
#include<queue>
using namespace std;

typedef struct {
  int i;
  int j;
}position;

void search(int a[][], int n, int i, int j, int cnt) {

  queue<position> qu = new queue<position>();

  position p;
  p.i = i;
  p.j = j;

  qu.push(p);
  a[i][j] = cnt;

  while (!qu.empty()) {
    p = qu.pop();

    for (int ii = p.i - 1; ii <= p.i + 1; ii++) {
      for (int jj = p.j - 1; jj <= p.j + 1; jj++) {
        if (ii >= 0 && ii < n && jj >= 0 && jj < n && a[ii][jj] == 1 && (ii != i || jj != j)) {
          a[ii][jj] = cnt;
          p.i = ii;
          p.j = jj;
          qu.push(p);
        }
      }
    }
  }
}

int count(int a[][], int n) {
  int cnt = 1;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      if (a[i][j] == 1) {
        cnt++; // 发现一个新陆地
        search(a, n, i, j, cnt);
      }
    }
  }
  return cnt;
}


int main() {

  int n;
  cin >> n;

  int a[][] = new int[n][n];
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      cin >> a[i][j];
    }
  }

  int cnt = count(a, n);

  cout << cnt - 1 << endl;


  return 0;
}