Leetcode Largest Number c++ solution
Total Accepted: 16020 Total Submissions: 103330
Given a list of non negative integers, arrange them such that they form the largest number.
For example, given [3, 30, 34, 5, 9], the largest formed number is 9534330.
Note: The result may be very large, so you need to return a string instead of an integer.
Credits:
Special thanks to @ts for adding this problem and creating all test cases.
会超过内存限制；把string改成char *就过了，但很难看!
bool comp(const string& a, const string& b) {
string x = a, y = b;
int diff = x.length() - y.length();
if (diff > 0) {
char c = y[0];
y.insert(y.end(), diff, c);
} else if (diff < 0) {
char c = y[0]; //lastChar(x);
x.insert(x.end(), -diff, c);
}
for (int i = 0; i < x.length(); i++) {
if (x[i] < y[i]) return false;
if (x[i] > y[i]) return true;
}
return comp(a+b, b+a);
}
class Solution {
public:
string largestNumber(vector<int> &num) {
int len = num.size();
string* snum = new string[len];
for (int i = 0; i < len; i++) {
snum[i] = to_string(num[i]);
}
stable_sort(snum, snum + len, comp);
string ret;
int i = 0;
for (; i < len && snum[i] == "0"; i++);
for (; i < len; i++)
ret += snum[i];
return ret.empty() ? "0" : ret;
}
};
把string改成char*
#define MAX_BUF 10
bool comp(char* a, char* b) {
char* x = a, *y = b;
char *short_, c[2];
int diff = strlen(x) - strlen(y);
short_ = diff > 0 ? y : x;
sprintf(c, "%c", short_[0]);
for (int i = 0; i < abs(diff); i++)
strcat(short_, c);
int len = strlen(x);
auto restore = [&]() {
for (int i = 0; i < abs(diff); i++)
short_[len - 1 - i] = '\0';
};
for (int i = 0; i < len; i++) {
if (x[i] < y[i]) {
restore();
return false;
}
if (x[i] > y[i]) {
restore();
return true;
}
}
restore();
if (strlen(x) == strlen(y)) return false;
char temp1[MAX_BUF*2], temp2[MAX_BUF*2];
sprintf(temp1, "%s%s", a, b);
sprintf(temp2, "%s%s", b, a);
return comp(temp1, temp2);
}
class Solution {
public:
string largestNumber(vector<int> &num) {
int len = num.size();
char** snum = new char*[len];
for (int i = 0; i < len; i++) {
snum[i] = new char[MAX_BUF];
sprintf(snum[i], "%d", num[i]);
}
sort(snum, snum + len, comp);
string ret;
int i = 0;
for (; i < len && strcmp(snum[i],"0") == 0; i++);
for (; i < len; i++)
ret += snum[i];
return ret.empty() ? "0" : ret;
}
};
重点来了，用python只需要几行
class Solution:
# @param num, a list of integers
# @return a string
def largestNumber(self, num):
num = sorted([str(x) for x in num], cmp = self.compare)
ans = ''.join(num).lstrip('0')
return ans or '0'
def compare(self, a, b):
return [1, -1][a + b > b + a]