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321.cpp
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321.cpp
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__________________________________________________________________________________________________
sample 16 ms submission
class Solution {
public:
#define MIN(a,b) (a<b?a:b)
#define MAX(a,b) (a>b?a:b)
// create max number of length t from single non-empty vector
void getMax(int* num, int& len, int* result, int& t, int& sortedLen)
{
int n, top = 0;
result[0] = num[0];
const int need2drop = len - t;
for (int i = 1; i < len; ++i){
n = num[i];
while (top >= 0 && result[top] < n && (i - top) <= need2drop) --top; // i - top means already dropped i - top numbers
if (i - top > need2drop){
sortedLen = MAX(1,top);
while (++top < t) result[top] = num[i++];
return;
}
if (++top < t) result[top] = n;
else top = t - 1;
}
}
// create max number of different length from single vector
void dp(int *num, int len, int&sortedLen, int& minL, int& maxL, int *res, int &k){
int j, *head, *prevhead = res;
const int soi = sizeof(int);
getMax(num, len, res, maxL,sortedLen);
for (int l = maxL; l > MAX(minL,1); --l){
head = prevhead + k;
memcpy(head, prevhead, l*soi);
for (j = sortedLen; j < l; ++j){
if (head[j] > head[j - 1]){
sortedLen = MAX(1, j - 1);
memcpy(head + j - 1, prevhead + j, soi*(l - j));
break;
}
}
if (j == l) sortedLen = l;
prevhead = head;
}
}
// merge max number created from single vector
void merge(int* num1,int len1,int* num2,int len2,int* result,int& resSize){
int i = 0, j = 0, k = 0;
while (i < resSize){
if (j < len1 && k < len2){
if (num1[j] > num2[k])
result[i++] = num1[j++];
else if (num1[j] < num2[k])
result[i++] = num2[k++];
else{
int remaining1 = len1 - j, remaining2 = len2 - k, tmp = num1[j];
int flag = memcmp(num1 + j, num2 + k, sizeof(int) * MIN(remaining1, remaining2));
flag = (flag == 0 ? (remaining1>remaining2 ? 1 : -1) : flag);
int * num = flag > 0 ? num1 : num2;
int & cnt = flag > 0 ? j : k;
int len = flag > 0 ? len1 : len2;
while (num[cnt]==tmp && cnt < len && i<resSize) result[i++] = num[cnt++];
}
}
else if (j < len1) result[i++] = num1[j++];
else result[i++] = num2[k++];
}
}
vector<int> maxNumber(vector<int>& nums1, vector<int>& nums2, int k){
int soi = sizeof(int), len1 = nums1.size(), len2 = nums2.size(), step = k*soi;
int minL1 = MAX(0, k - len2), maxL1 = MIN(k, len1), minL2 = k - maxL1, maxL2 = k - minL1, range = maxL1 - minL1 + 1;
int * res = new int[range * k * 2 + 2 * k], *dp1 = res + k, *dp2 = res + range*k+k, *tmp=res+range*2*k+k;
memset(res, 0, step);
int sortedLen1 = 1, sortedLen2 = 1;
if (len1 == 0 && len2 > 0) getMax(&nums2[0], len2, res, k, sortedLen2);
else if (len1 > 0 && len2 == 0) getMax(&nums1[0], len1, res, k, sortedLen2);
else if (len1 > 0 && len2 > 0){
dp(&nums1[0], len1, sortedLen1, minL1, maxL1, dp1,k);
dp(&nums2[0], len2, sortedLen2, minL2, maxL2, dp2,k);
if (sortedLen1 + sortedLen2 > k){
merge(dp1 + k*(maxL1 - sortedLen1), sortedLen1, dp2 + k*(maxL2 - sortedLen2), sortedLen2, tmp, k);
vector<int> resv(tmp, tmp + k);
delete[] res;
return resv;
}
for (int i = minL1; i <= maxL1; ++i){
merge(dp1+k*(maxL1-i), i, dp2+k*(maxL2-k+i), (k-i), tmp,k);
if (memcmp(res, tmp, step) < 0) memcpy(res, tmp, step);
}
}
vector<int> resv(res, res + k);
delete[] res;
return resv;
}
};
__________________________________________________________________________________________________
sample 14400 kb submission
class Solution {
public:
vector<int> maxNumber(vector<int>& a, vector<int>& b, int k) {
if (!k) {
return {};
}
vector<int> ret(k, 0);
if (a.size() + b.size() < k) {
return ret;
}
if (a.size() + b.size() == k) {
return merge_top_k(a, b);
}
int begin = max(0, k-(int)b.size());
int last = min((int)a.size(), k);
for (int i = begin; i <= last; i++) {
auto temp = merge_top_k(top_k(a, i), top_k(b, k-i));
ret = max(ret, temp);
}
return ret;
}
private:
template<typename iterator>
bool compare(iterator from, iterator last, iterator begin, iterator end) {
while (from < last && begin < end && *from == *begin) {
from++;
begin++;
}
if (from < last && begin < end) {
return *from < *begin;
}
// from is larger
if (from < last) {
return false;
}
return true;
}
vector<int> merge_top_k(vector<int> a, vector<int> b) {
auto iter = a.begin();
auto jter = b.begin();
vector<int> ret(a.size() + b.size(), 0);
int t = 0;
while (iter < a.end() || jter < b.end()) {
if (jter == b.end() || iter < a.end() && *iter > *jter) {
ret[t++] = *iter++;
} else if (iter < a.end() && jter < b.end() && *iter == *jter) {
bool less = compare(iter, a.end(), jter, b.end());
if (!less) {
ret[t++] = *iter++;
} else {
ret[t++] = *jter++;
}
} else {
ret[t++] = *jter++;
}
}
return ret;
}
vector<int> top_k(vector<int> &nums, int k)
{
vector<int> result;
if (k == 0)
return result;
result = vector<int>(k, 0);
int j = 0;
int n = nums.size();
for (int i = 0; i < n; i++)
{
// 出栈操作
while (j > 0 && n - i + j > k && nums[i] > result[j - 1])
j--;
// 入栈操作
if (j < k)
result[j++] = nums[i];
}
return result;
}
};
__________________________________________________________________________________________________