104. 建造最大岛屿

题目

链接

代码

import java.util.*;
class Main{public static void main(String[] args){Scanner sc = new Scanner(System.in);int N = sc.nextInt();//行int M = sc.nextInt();//列int[][] pic = new int[N][M];used = new boolean[N][M];for(int i =0;i<N;i++){for(int j =0;j<M;j++){pic[i][j] = sc.nextInt();if(pic[i][j]==0){used[i][j] = true;}}}int maxCount = 0;int index = 1;Map<Integer,Integer> map = new HashMap(); for(int i =0;i<N;i++){for(int j =0;j<M;j++){if(pic[i][j]==1){list.clear();dfs(pic,i,j);for(int k = 0;k<list.size();k++){int[] temp= list.get(k);pic[temp[0]][temp[1]] = index;}map.put(index,list.size());maxCount = Math.max(maxCount,list.size());index++;}}}for(int i =0;i<N;i++){for(int j =0;j<M;j++){if(pic[i][j]==0){Set<Integer> sett = new HashSet();int count = 1;if(i>=1 && !sett.contains(pic[i-1][j])){count+=map.getOrDefault(pic[i-1][j],0);sett.add(pic[i-1][j]);}if(j>=1 && !sett.contains(pic[i][j-1])){count+=map.getOrDefault(pic[i][j-1],0);sett.add(pic[i][j-1]);}if(i<pic.length-1 && !sett.contains(pic[i+1][j])){count += map.getOrDefault(pic[i+1][j],0);sett.add(pic[i+1][j]);}if(j<pic[0].length-1 && !sett.contains(pic[i][j+1])){count+=map.getOrDefault(pic[i][j+1],0);sett.add(pic[i][j+1]);}maxCount = Math.max(maxCount,count);}}}System.out.println(maxCount);}static boolean[][] used;static List<int[]> list = new ArrayList();public static void dfs(int[][] pic,int i,int j){if(i<0||j<0||i>=pic.length||j>=pic[0].length||used[i][j]){return;}used[i][j] = true;list.add(new int[]{i,j});if(i>=1){dfs(pic,i-1,j);}if(j>=1){dfs(pic,i,j-1);}if(i<pic.length-1){dfs(pic,i+1,j);}if(j<pic[0].length-1){dfs(pic,i,j+1);}}
}

110. 字符串接龙

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链接

代码

import java.util.*;class Main{public static void main(String[] args){Scanner sc = new Scanner(System.in);int N = Integer.valueOf(sc.nextLine());String beginStr = sc.next();String endStr = sc.next();Set<String> strList = new HashSet();for(int i = 0;i<N;i++){strList.add(sc.next());}int count = 0;Deque<String>  queue = new LinkedList();queue.addLast(beginStr);while(!queue.isEmpty()){count++;int size = queue.size();for(int step = 0;step<size;step++){String word = queue.removeFirst();for(int i=0;i< word.length();i++){char[] chars = word.toCharArray();for(char k = 'a';k<='z';k++){chars[i] = k;   String newWord = String.valueOf(chars);if(newWord.equals(endStr)){System.out.println(count+1);return;}if(strList.contains(newWord)){strList.remove(newWord);queue.addLast(newWord);}}}}}System.out.println(0);}
}

105. 有向图的完全可达性

题目

链接

代码

import java.util.*;class Main{public static void main(String[] args){Scanner sc = new Scanner(System.in);int N = sc.nextInt();int K = sc.nextInt();Map<Integer,Set<Integer>> map = new HashMap();for(int i =1;i<=N;i++){map.put(i,new HashSet());}for(int i = 0;i<K;i++){int num1 = sc.nextInt();int num2 = sc.nextInt();map.get(num1).add(num2);}used = new boolean[N+1];dfs(map,1);for(int i =1;i<=N;i++){if(!used[i]){System.out.println(-1);return;}}System.out.println(1);}static boolean[] used;public static void dfs(Map<Integer,Set<Integer>> map,int key){if(used[key]){return;}used[key] = true;Set<Integer> set =map.get(key);for(int nextNum:set){dfs(map,nextNum);}}
}

106. 岛屿的周长

题目

链接

代码

import java.util.*;class Main{public static void main(String[] args){Scanner sc = new Scanner(System.in);int N = sc.nextInt();int M = sc.nextInt();int[][] pic = new int[N][M];for(int i=0;i<N;i++){for(int j=0;j<M;j++){pic[i][j] = sc.nextInt();}}int sum = 0;    // 陆地数量int cover = 0;  // 相邻数量for (int i = 0; i < N; i++) {for (int j = 0; j < M; j++) {if (pic[i][j] == 1) {sum++; // 统计总的陆地数量// 统计上边相邻陆地if(i - 1 >= 0 && pic[i - 1][j] == 1) cover++;// 统计左边相邻陆地if(j - 1 >= 0 && pic[i][j - 1] == 1) cover++;// 为什么没统计下边和右边？ 因为避免重复计算}}}System.out.println(sum * 4 - cover * 2 );}
}