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| class Solution {
private:
int countOnes(int n) {
int ones = 0;
while (n) {
n &= (n - 1);
++ones;
}
return ones;
}
public:
vector<int> countBits(int num) {
vector<int> ans(num + 1);
for (int i = 0; i <= num; ++i)
ans[i] = countOnes(i);
return ans;
}
};
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| class Solution {
public:
vector<int> countBits(int num) {
vector<int> dp(num + 1);
int highBit = 0;
for (int i = 1; i <= num; ++i) {
if ((i & (i - 1)) == 0)
highBit = i;
dp[i] = dp[i - highBit] + 1;
}
return dp;
}
};
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| class Solution {
public:
vector<int> countBits(int num) {
vector<int> dp(num + 1);
for (int i = 1; i <= num; ++i)
dp[i] = dp[i >> 1] + (i & 1);
return dp;
}
};
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| class Solution {
public:
vector<int> countBits(int num) {
vector<int> dp(num + 1);
for (int i = 1; i <= num; ++i)
dp[i] = dp[i & (i - 1)] + 1;
return dp;
}
};
|
Reference: 比特位计数 - 比特位计数 - 力扣（LeetCode）