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611.cpp
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611.cpp
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__________________________________________________________________________________________________
sample 12 ms submission
class Solution {
public:
int triangleNumber(vector<int>& nums) {
sort(nums.begin(), nums.end());
int res = 0;
for (auto i = nums.cend(); i != nums.cbegin();) {
--i;
auto iv = *i;
auto j = nums.cbegin();
auto k = i;
--k;
while(j < k) {
if (*j + *k > iv) {
res += distance(j, k);
--k;
} else {
++j;
}
}
}
return res;
}
};
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sample 9656 kb submission
class Solution {
public:
int triangleNumber(vector<int>& nums) {
int ans = 0;
if(nums.size() < 3) {
return ans;
}
sort(nums.begin(), nums.end());
for(int i = 0; i < nums.size() - 2; ++ i){
for(int j = i + 1; j < nums.size() - 1; ++ j){
ans += getNumOfTriangles(nums[i] + nums[j], j, nums);
}
}
return ans;
}
private:
int getNumOfTriangles(int upbnd, int start, vector<int>& nums){
int l = start + 1, r = nums.size() - 1;
int res = start;
while(l <= r){
int mid = (l + r)>>1;
if(nums[mid] < upbnd){
res = max(res, mid);
l = mid + 1;
} else {
r = mid - 1;
}
}
return res - start;
}
};
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