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wk299.java
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wk299.java
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package weekly;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
public class wk299 {
//ranking: 466 / 6792
//简单题，知道怎么判断对角线就行
public boolean checkXMatrix(int[][] grid) {
for (int i = 0; i < grid.length; i++) {
for (int j = 0; j < grid[0].length; j++) {
if (i == j || i + j + 1 == grid[0].length) {
if (grid[i][j] == 0) return false;
} else {
if (grid[i][j] != 0) return false;
}
}
}
return true;
}
//中等题，像极了打家劫舍？
public int countHousePlacements(int n) {
int mod = (int) 1e9 + 7;
long[] dp = new long[2];
dp[0] = 1;//0也是一种情况
dp[1] = 0;
for (int i = 0; i < n; i++) {
long[] ndp = new long[2];
ndp[0] = dp[0] + dp[1];
ndp[1] = dp[0];
ndp[0] %= mod;
ndp[1] %= mod;
dp = ndp;
}
//最后的结果做乘法 是组合
long res = (dp[0] + dp[1]) * (dp[0] + dp[1]);
res %= mod;
return (int) res;
}
//
static public int maximumsSplicedArray(int[] nums1, int[] nums2) {
return Math.max(help(nums1, nums2), help(nums2, nums1));
}
static public int help(int[] nums1, int[] nums2) {
int res = 0;
int[] num = new int[nums1.length];
//求差值
for (int i = 0; i < nums1.length; i++) {
res += nums1[i];
num[i] = nums2[i] - nums1[i];
}
int sum = 0;
int left = 0;
int max = 0;
//最大子数组和 滑动窗口，不用滑动窗口也行
/* for (int i = 0; i < num.length; i++) {
sum += num[i];
while (sum < 0) {
sum -= num[left++];
}
max = Math.max(sum, max);
}*/
for (int i = 0; i < num.length; i++) {
sum += num[i];
if (sum < 0) {
sum = 0;
}
max = Math.max(sum, max);
}
return res + max;
}
//困难题，太暴力了过不了的..看了大佬的提示自己做出来了
//枚举+分类讨论，即枚举的时候判断是不是子树，
public int minimumScore(int[] nums, int[][] edges) {
Map<Integer, List<Integer>> map = new HashMap<>();
for (int[] edge : edges) {
if (!map.containsKey(edge[0])) map.put(edge[0], new ArrayList<>());
if (!map.containsKey(edge[1])) map.put(edge[1], new ArrayList<>());
map.get(edge[0]).add(edge[1]);
map.get(edge[1]).add(edge[0]);
}
int[] xors = new int[nums.length];
dfs(xors, 0, map, new boolean[nums.length], nums);
int ans = Integer.MAX_VALUE;
for (int i = 0; i < nums.length; i++) {
for (int j = i; j < nums.length; j++) {
if (i == 0 || j == 0) continue;//跳过根节点
if (i == j) continue;
int max = 0;
int min=Integer.MAX_VALUE;
//是子树的情况
if (set.get(i).contains(j)) {
max = Math.max(xors[i] ^ xors[j], Math.max(xors[j], xors[0] ^ xors[i]));
min=Math.min(xors[i] ^ xors[j], Math.min(xors[j], xors[0] ^ xors[i]));
} else if (set.get(j).contains(i)) {
max = Math.max(xors[j] ^ xors[i], Math.max(xors[i], xors[0] ^ xors[j]));
min = Math.min(xors[j] ^ xors[i], Math.min(xors[i], xors[0] ^ xors[j]));
//不是子树的情况
} else {
max = Math.max(xors[i], Math.max(xors[j], xors[0] ^ xors[j] ^ xors[i]));
min = Math.min(xors[i], Math.min(xors[j], xors[0] ^ xors[j] ^ xors[i]));
}
ans = Math.min(ans, max-min);
}
}
return ans;
}
//记录子树 应该有更好的记录办法
Map<Integer, Set<Integer>> set = new HashMap<>();
//dfs求每个点及其子树的异或
int dfs(int[] xors, int index, Map<Integer, List<Integer>> map, boolean[] visited, int[] nums) {
int xor = nums[index];
Set<Integer> s = new HashSet<>();
s.add(index);
visited[index]=true;
for (Integer next : map.getOrDefault(index, new LinkedList<>())) {
if (visited[next]) continue;
visited[next] = true;
xor ^= dfs(xors, next, map, visited, nums);
s.addAll(set.get(next));
}
xors[index] = xor;
set.put(index, s);
return xor;
}
public static void main(String[] args) {
wk299 w=new wk299();
w.minimumScore(new int[]{1,5,5,4,11},new int[][]{
{0,1},{1,2},{1,3},{3,4}
});
}
/* public int minimumScore(int[] nums, int[][] edges) {
Map<Integer, List<Integer>> map = new HashMap<>();
for (int[] edge : edges) {
if (!map.containsKey(edge[0])) map.put(edge[0], new ArrayList<>());
if (!map.containsKey(edge[1])) map.put(edge[1], new ArrayList<>());
map.get(edge[0]).add(edge[1]);
map.get(edge[1]).add(edge[0]);
}
int res = Integer.MAX_VALUE;
for (int i = 0; i < edges.length; i++) {
for (int j = i; j < edges.length; j++) {
if (i == j) continue;
res = Math.min(res, help(nums, edges, i, j, map));
}
}
return res;
}
int help(int[] nums, int[][] edges, int a, int b, Map<Integer, List<Integer>> map) {
int[] edgeA = edges[a];
int[] edgeB = edges[b];
List<Integer> list = new ArrayList<>();
list.add(edgeA[0]);
list.add(edgeA[1]);
list.add(edgeB[0]);
list.add(edgeB[1]);
int max = 0, min = Integer.MAX_VALUE;
for (Integer integer : list) {
int bfs = bfs(nums, a, b, edges,integer, map);
max = Math.max(max, bfs);
min = Math.min(min, bfs);
}
System.out.println(a+" "+b);
System.out.println(max +"" + min);
return max - min;
}
int bfs(int[] nums, int a, int b,int[][] edges, int from, Map<Integer, List<Integer>> map) {
Queue<Integer> queue = new LinkedList<>();
queue.add(from);
int sum = 0;
boolean[] visited = new boolean[nums.length];
visited[from] = true;
while (!queue.isEmpty()) {
Integer index = queue.poll();
sum ^= nums[index];
for (Integer next : map.getOrDefault(index, new ArrayList<>())) {
if (index == edges[a][0] && next == edges[a][1]) continue;
if (index == edges[a][1] && next == edges[a][0]) continue;
if (index == edges[b][0] && next == edges[b][1]) continue;
if (index == edges[b][1] && next == edges[b][0]) continue;
if (visited[next]) continue;
queue.add(next);
visited[next] = true;
}
}
return sum;
}*/
}