20240825蚂蚁后端笔试前两题ac
- (a==b)&&(d==0 || a>0)为YES
- dfs预处理一份全部的好数列表，对每次询问二分答案
static int[] goodNums = new int[5680000];
static int p = 0;
static {
for (int i = 1; i <= 9; i++) {
dfs(0, i, 0, 0);
}
goodNums[p++] = 1023456789;
}
static void dfs(int pos, int n, int mask, int curNum) {
if (pos == n) {
goodNums[p++] = curNum;
return;
}
for (int i = 0; i <= 9; i++) {
if (i == 0 && pos == 0) {
continue;
}
if (((mask >> i) & 1) == 0) {
dfs(pos + 1, n, mask | (1 << i), curNum * 10 + i);
}
}
}
