LeetCode 1020 Number of Enclaves
题目分析
https://leetcode.com/problems/number-of-enclaves/
基本上与 https://leetcode.com/problems/number-of-closed-islands 一致，无非是这里统计元素个数而非岛屿个数。
深度优先搜索
class Solution {
public:
int numEnclaves(vector<vector<int>>& grid) {
int count = 0;
for (int i=0; i<grid.size(); i++) {
for (int j=0; j<grid[0].size(); j++) {
if (grid[i][j] == 1) {
int cnt = 0;
if (travelIsland(i, j, grid, cnt)) {
count += cnt;
}
}
}
}
return count;
}
bool travelIsland(int i, int j, vector<vector<int>>& grid, int& count) {
if (i < 0 || j < 0 || i >= grid.size() || j >= grid[0].size()) return false;
if (grid[i][j] == 1) {
grid[i][j] = 2; // mark as visited island
count += 1;
bool f1 = travelIsland(i+1, j, grid, count);
bool f2 = travelIsland(i-1, j, grid, count);
bool f3 = travelIsland(i, j+1, grid, count);
bool f4 = travelIsland(i, j-1, grid, count);
return f1 && f2 && f3 && f4;
}
return true;
}
};