科大讯飞笔试AC代码
public int changeNumber (int num) {
int a = -1;
int cur = 0;
int z = num;
while(cur<2){
if((z&1)==0) cur++;
z=z>>1;
a++;
}
return num|(1<<a);
} 第二题。写得不太简略
public int findInterval (String str) {
char[] cs = str.toCharArray();
if(cs.length<26) return -1;
int[] times = new int[26];
int left = 0;
int right = -1;
boolean flag = false;
int n = cs.length;
int curNumber = 0;
int minRes = Integer.MAX_VALUE;
while(right<n-1){
if(!flag){
right++;
char c = cs[right];
if(c=='?') curNumber++;
else if (times[c-'a']>0){
times[c-'a']++;
continue;
} else {
curNumber++;
times[c-'a']++;
}
if(curNumber>=26){
minRes=Math.min(minRes,right-left+1);
flag=true;
}
continue;
}
if(flag){
char c = cs[left];
left++;
if(c=='?') curNumber--;
else if (times[c-'a']==1){
curNumber--;
times[c-'a']-=1;
} else times[c-'a']-=1;
if(curNumber>=26){
minRes=Math.min(minRes,right-left+1);
} else flag=false;
}
}
while(left<n-1&&flag){
char c = cs[left];
left++;
if(c=='?') curNumber--;
else if (times[c-'a']==1){
curNumber--;
times[c-'a']-=1;
} else times[c-'a']-=1;
if(curNumber>=26){
minRes=Math.min(minRes,right-left+1);
} else flag=false;
}
return minRes==Integer.MAX_VALUE?-1:minRes;
} 第三题
HashMap<TreeNode, LinkedList<Integer>> map;
int res;
public int leafPairs (TreeNode root, int k) {
res=0;
map = new HashMap<>();
dfs(root,k);
return res;
}
public LinkedList<Integer> dfs(TreeNode cur,int k){
if(cur==null) return new LinkedList<>();//长度为0
if(cur.left==null&&cur.right==null){//叶子节点的list长度为1
LinkedList<Integer> list = new LinkedList<>();
list.add(1);
return list;//List长度为1
}
LinkedList<Integer> list0 = dfs(cur.left,k);//代表叶子节点数,叶子节点的节点数
LinkedList<Integer> list1 = dfs(cur.right,k);
LinkedList<Integer> myList = new LinkedList<>();
myList.add(0);//当前节点不是叶子节点.
//left.get(a)*right.get(b) where k = a+b+2;
for(int x = 0 ; k-x-2>=0 ; x++){
int y = k-x-2;
int ans0 = list0.size()>x?list0.get(x):0;
int ans1 = list1.size()>y?list1.get(y):0;
res+=(ans0*ans1);
}
Iterator<Integer> itr0 = list0.iterator();
Iterator<Integer> itr1 = list1.iterator();
while(true){
if(!itr0.hasNext() && !itr1.hasNext()) break;
int c = itr0.hasNext()?itr0.next():0;
int d = itr1.hasNext()?itr1.next():0;
myList.add(c+d);
}
return myList;
} 
