题解 | #数字在升序数组中出现的次数#
数字在升序数组中出现的次数
http://www.nowcoder.com/practice/70610bf967994b22bb1c26f9ae901fa2
1
认识到上下界
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class Solution {
public:
int GetNumberOfK(vector<int> nums ,int target) {
int lbound = 0, rbound = 0;
// 寻找xia界
int l = 0, r = nums.size();
while (l < r) {
int mid = l + (r - l) / 2;
if (nums[mid] < target) {
l = mid + 1;
}
else {
r = mid;
}
}
lbound = l;
// 寻找shang界
l = 0, r = nums.size();
while (l < r) {
int mid = l + (r - l) / 2;
if (nums[mid] <= target) {
l = mid + 1;
}
else {
r = mid;
}
}
rbound = r;
return rbound - lbound;
}
};
