class Solution {
public intxorOperation(int n,int start){int res = start;for(int i=1;i<n;i++){
start = start+2;
res^=start;}return res;}}
1487. 保證文件名唯一
class Solution {
public String[]getFolderNames(String[] names){if(names == null || names.length==0){return null;}int len = names.length;
String[] res = new String[len];
Map<String,Integer> map = new HashMap<String,Integer>();for(int i=0;i<len;i++){//不包含if(!map.containsKey(names[i])){
res[i]= names[i];
map.put(names[i],1);}else{int count=map.get(names[i]);while(map.containsKey(names[i]+"("+ count +")")){
count++;}
map.put(names[i]+"("+ count +")",1);
map.put(names[i], map.get(names[i])+1);// 本次的結果
res[i]= names[i]+"("+ count +")";}}return res;}}
1488. 避免洪水氾濫
class Solution {
public int[]avoidFlood(int[] rains){int len = rains.length;int[] res = new int[len];
Map<Integer,Integer> water = new HashMap<Integer,Integer>();
TreeSet<Integer> zero = new TreeSet<Integer>();for(int i=0;i<len;i++){int r = rains[i];//System.out.println("r:"+r);if(r==0){
res[i]=1;
zero.add(i);continue;}if(water.containsKey(r)){int preIdx = water.get(r);
Integer zeroIdx = zero.higher(preIdx);if(zeroIdx==null){return new int[0];}
zero.remove(zeroIdx);
res[zeroIdx]= r;}
water.put(r,i);
res[i]=-1;}return res;}}