题目
https://leetcode-cn.com/problems/find-first-and-last-position-of-element-in-sorted-array/
解法
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| public int binarySearch (int[] nums, int target) {
if (nums==null||nums.length==0) {
return -1;
}
int left=0, right=nums.length-1;
while (left<=right) {
int mid = left + ((right-left)>>1);
if (nums[mid] == target) {
return mid;
} else if (nums[mid] < target) {
left = mid+1;
} else if (nums[mid] > target) {
right = mid-1;
}
}
return -1;
}
int left_bound(int[] nums, int target) {
if (nums==null||nums.length==0) {
return -1;
}
int left=0, right = nums.length-1;
while (left<=right) {
int mid = left + ((right-left)>>1);
if (nums[mid] < target) {
left = mid + 1;
} else if(nums[mid]>target) {
right = mid - 1;
} else if (nums[mid] == target) {
right = mid - 1;
}
}
if (left>=nums.length || nums[left] != target) {
return -1;
}
return left;
}
int right_bound(int[] nums, int target) {
if (nums==null||nums.length==0) {
return 0;
}
int left=0, right=nums.length-1;
while (left<=right) {
int mid = left+((right-left)>>1);
if (nums[mid] == target) {
left = mid + 1;
} else if (nums[mid] < target) {
left = mid + 1;
} else if(nums[mid] > target) {
right = mid - 1;
}
}
if (right<0 || nums[right] != target) {
return -1;
}
return right;
}
|
