文章目录
金币
题目链接：https://www.lanqiao.cn/problems/357/learning/
package daily;
import java.util.Scanner;
/**
* https://www.lanqiao.cn/problems/357/learning/
*
* @author Jia
*
*/
public class day3_23_1 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int K = sc.nextInt();
sc.close();
long ans = 0;// 答案
int day = 0;// 天数
int i = 1;// 这天发几个硬币
while (day < K) {
for (int j = 0; j < i; j++) {
ans += i;
day++;
if (day >= K) {
break;
}
}
i++;
}
System.out.println(ans);
}
}
优秀的拆分
题目链接：https://www.lanqiao.cn/problems/801/learning/
package daily;
import java.util.ArrayList;
import java.util.Scanner;
/**
* https://www.lanqiao.cn/problems/801/learning/
*
* @author Jia
*
*/
public class day3_23_2 {
static ArrayList<Integer> ans = new ArrayList<>();
static int sum = 0;
static boolean find = false;
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
sc.close();
ArrayList<Integer> list = init(n);// 获得小于输入整数n的所有2的次幂
backtrack(list, list.size() - 1, n);
if (find == false) {
// 当没找到时输出-1
System.out.println(-1);
}
}
/**
* 回溯法寻找子集树
*
* @param list
* @param index
* @param target
*/
private static void backtrack(ArrayList<Integer> list, int index, int target) {
if (sum == target) {
// 当找到一种组合时直接打印出结果，并且设置当前状态为已经找到，不再遍历后面的分支
find = true;
for (int i = 0; i < ans.size(); i++) {
System.out.print(ans.get(i) + " ");
}
} else {
for (int i = index; i >= 0; i--) {
if (sum + list.get(i) <= target && !find) {
ans.add(list.get(i));
sum += list.get(i);
backtrack(list, i - 1, target);
sum -= ans.remove(ans.size() - 1);
}
}
}
}
/**
* 获得小于输入整数n的所有2的次幂
*
* @param n
* @return
*/
private static ArrayList<Integer> init(int n) {
ArrayList<Integer> list = new ArrayList<>();
int i = 2;
while (i <= n) {
list.add(i);
i = i * 2;
}
return list;
}
}
穿越雷区
题目链接：http://lx.lanqiao.cn/problem.page?gpid=T2818
package daily;
import java.util.Deque;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Scanner;
import java.util.Set;
/**
* http://lx.lanqiao.cn/problem.page?gpid=T2818
*
* @author Jia
*
*/
public class day3_23_3 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
char[][] zone = new char[n][n];
ZoneNode A = new ZoneNode();
ZoneNode B = new ZoneNode();
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
zone[i][j] = sc.next().charAt(0);
if (zone[i][j] == 'A') {
A.set(i, j, 'A');
} else if (zone[i][j] == 'B') {
B.set(i, j, 'B');
}
}
}
sc.close();
// 参数初始化
Deque<ZoneNode> queue = new LinkedList<>();
queue.addFirst(A);
Set<ZoneNode> set = new HashSet<>();
set.add(A);
int[] nextRow = { 0, -1, 0, 1 };
int[] nextCol = { 1, 0, -1, 0 };
boolean flag = false;
int ans = 0;
// bfs遍历
while (!queue.isEmpty()) {
int size = queue.size();
ans++;
while (size > 0) {
ZoneNode node = queue.removeLast();
size--;
// 四个方向看看
for (int i = 0; i < nextRow.length; i++) {
int newRow = node.row + nextRow[i];
int newCol = node.col + nextCol[i];
if (bound(n, newRow, newCol)) {
if (zone[newRow][newCol] == 'B') {
flag = true;
break;
}
ZoneNode newNode = new ZoneNode(newRow, newCol, zone[newRow][newCol]);
if (constrain(set, node, newNode)) {
queue.addFirst(newNode);
set.add(newNode);// 去重
}
}
}
if (flag) {
break;
}
}
if (flag) {
break;
}
}
System.out.println(ans);
}
/**
* 是否在题目给出的区域范围中
*
* @param n
* @param newRow
* @param newCol
* @return
*/
private static boolean bound(int n, int newRow, int newCol) {
return newRow >= 0 && newRow < n && newCol >= 0 && newCol < n;
}
/**
* 判断下一个格子能不能走
*
* 1.这个格子没有走过（所有都必须满足）
*
* 2.当前格子如果是A的话，则下一个格子可以走
*
* 3.当前格子是 + ，则下一个格子是 - 才可以走，反之亦然
*
* @param set
* @param node
* @param newNode
* @return
*/
private static boolean constrain(Set<ZoneNode> set, ZoneNode node, ZoneNode newNode) {
return !set.contains(newNode) && (node.symbol == 'A' || (node.symbol == '-' && newNode.symbol == '+')
|| (node.symbol == '+' && newNode.symbol == '-'));
}
}
class ZoneNode {
int row;
int col;
char symbol;
@Override
public boolean equals(Object obj) {
ZoneNode otherNode = (ZoneNode) obj;
return row == otherNode.row && col == otherNode.col;
}
@Override
public int hashCode() {
return row * 101 + col * 102;
}
public ZoneNode() {
super();
}
public ZoneNode(int row, int col, char symbol) {
super();
this.row = row;
this.col = col;
this.symbol = symbol;
}
public void set(int row, int col, char symbol) {
this.row = row;
this.col = col;
this.symbol = symbol;
}
}
蓝肽子序列
题目链接：https://www.lanqiao.cn/problems/1030/learning/
package daily;
import java.util.ArrayList;
import java.util.Scanner;
/**
* https://www.lanqiao.cn/problems/1030/learning/
*
* @author Jia
*
*/
public class day3_23_4 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
String str1 = sc.nextLine();
String str2 = sc.nextLine();
sc.close();
ArrayList<String> arr1 = splitString(str1);
ArrayList<String> arr2 = splitString(str2);
// 动态规划求最优解
int[][] dp = new int[arr1.size() + 1][arr2.size() + 1];
for (int i = 1; i < dp.length; i++) {
String subStr1 = arr1.get(i - 1);
for (int j = 1; j < dp[0].length; j++) {
String subStr2 = arr2.get(j - 1);
if (subStr1.equals(subStr2)) {
// 当前指向的两个元素相等，则直接是出去这两个元素的子序列的最大长度+1
dp[i][j] = dp[i - 1][j - 1] + 1;
} else {
// 如果当前两个元素不等，则要取删除掉第一个数组或者第二个数组当前元素这两种情况的最长长度
dp[i][j] = Math.max(dp[i - 1][j], dp[i][j - 1]);
}
}
}
System.out.println(dp[arr1.size()][arr2.size()]);
}
/**
* 将字符串拆分成单词的形式
*
* @param str
* @return
*/
private static ArrayList<String> splitString(String str) {
ArrayList<String> list = new ArrayList<>();
StringBuilder sb = new StringBuilder();
for (int i = 0; i < str.length(); i++) {
if (Character.isUpperCase(str.charAt(i))) {
// 如果是大写的则需要将当前创建好的字符串加入list，然后清空StringBilder
if (sb.length() != 0) {
list.add(sb.toString());
sb = new StringBuilder();
}
}
sb.append(str.charAt(i));
}
list.add(sb.toString());
return list;
}
}
