Spring Boot入门 leetcode

学习目标：

学习SpringBoot 

求解leetcode51

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学习内容：

学习如何建立一个SpringBoot项目，并且完成了第一个接口的开发，了解了多种配置URL的方式，熟悉了配置文件的两种写法。

leetcode51:

public class L51 {
    public List> solveNQueens(int n) {
        //1.n x n
        char[][] board = new char[n][n];
        for (int i = 0; i < n; i++) {
            for(int j=0;j> result = new ArrayList<>();
        backtrack(result,0,n,board);
        return result;
    }

    public void backtrack(List> result, int row, int n, char[][] board) {
        //if满足结束条件
        if (row == n) {
            result.add(arrayToList(board));
            return;
        }
        for (int col= 0; col < n; col++) {
            if (!isValid(row, col, board)) {
                continue;
            }
            board[row][col] = 'Q';
            backtrack(result, row + 1, n, board);
            board[row][col] = '.';
        }
    }
    //把数组转换成列表满足题目要求
    public List arrayToList(char[][] board) {
        List list = new ArrayList<>();
        for (int i = 0; i < board.length; i++) {
            StringBuilder builder = new StringBuilder();
            for (int j = 0; j < board.length; j++) {
                builder.append(board[i][j]);
            }
            list.add(builder.toString());
        }
        return list;
    }

    //判断当前位置(row,col)的皇后是否合法
    public boolean isValid(int row, int col, char[][] board) {
        //行
        for (int temCol = 0; temCol < board.length; temCol++) {
            if (board[row][temCol] == 'Q') {
                return false;
            }
        }
        //列
        for (int tmpRow = 0; tmpRow < board.length; tmpRow++) {
            if (board[tmpRow][col] == 'Q') {
                return false;
            }
        }
        //45度角
        for (int i = row - 1, j = col + 1; j <= board.length-1&& i >= 0; i--, j++) {
            if (board[i][j] == 'Q') {
                return false;
            }
        }
        //135度角
        for (int i = row - 1, j = col - 1; j >= 0 && i >= 0; i--, j--) {
            if (board[i][j] == 'Q') {
                return false;
            }
        }
        return true;
    }
    public static void main(String[] args) {
        int n=7;
        System.out.println(new L51().solveNQueens(n));
    }
}

leetcode349:

import java.util.ArrayList;
import java.util.TreeSet;
public class L349 {
    public int[] intersection(int[] nums1, int[] nums2) {
        TreeSet set = new TreeSet<>();
        for (int num : nums1) {
            set.add(num);
        }
        ArrayList list = new ArrayList<>();
        for (int num : nums2) {
            if (set.contains(num)) {
                list.add(num);
                set.remove(num);
            }
        }
        int[] res = new int[list.size()];
        for (int i = 0; i < list.size(); i++) {
            res[i] = list.get(i);
        }
        return res;
    }
}

leetcode350:

import java.util.ArrayList;
import java.util.TreeMap;
public class L350 {
    public int[] intersect(int[] nums1, int[] nums2) {
        TreeMap map = new TreeMap<>();
        for (int num : nums1) {
            if (!map.containsKey(num))
                map.put(num, 1);
            else
                map.put(num, map.get(num) + 1);
        }
        ArrayList list = new ArrayList<>();
        for (int num : nums2) {
            if (map.containsKey(num)) {
                list.add(num);
                map.put(num, map.get(num) - 1);
                if (map.get(num) == 0) {
                    map.remove(num);
                }
            }
        }
        int[] res = new int[list.size()];
        for (int i = 0; i < list.size(); i++) {
            res[i] = list.get(i);
        }
        return res;
    }
}

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学习时间：

08：00-10：00 11：30-12：00 18：00-19：00

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学习产出：

掌握了SpringBoot的创建与配置。