704.二分查找
class Solution {
public int search(int[] nums, int target) {
if(nums.length == 0)
return -1;
int start = 0;
int end = nums.length - 1;
int mid;
while(start + 1 < end) {
mid = start + (end - start) / 2;
if(nums[mid] == target) {
end = mid;
} else if(nums[mid] < target) {
start = mid;
} else if(nums[mid] > target) {
end = mid;
}
}
if(nums[start] == target) {
return start;
}
if(nums[end] == target) {
return end;
}
return -1;
}
}
35.搜索插入位置
套模板
class Solution {
public int searchInsert(int[] nums, int target) {
if(nums.length == 0)
return -1;
int start = 0;
int end = nums.length - 1;
int mid;
while(start + 1 < end) {
mid = start + (end - start) / 2;
if(nums[mid] == target) {
end = mid;
} else if(nums[mid] < target) {
start = mid;
} else if(nums[mid] > target) {
end = mid;
}
}
if (nums[start] >= target) {
return start;
} else if (nums[end] >= target) {
return end;
} else {
return end + 1;
}
}
}
74.搜索二維矩陣
class Solution {
public boolean searchMatrix(int[][] matrix, int target) {
if(matrix.length == 0 || matrix[0].length == 0)
return false;
int start = 0;
int rol = matrix.length, col = matrix[0].length;
int end = rol * col - 1,mid;
while(start + 1 < end) {
mid = start + (end - start) / 2;
if (matrix[mid / col][mid % col] == target)
return true;
else if (matrix[mid / col][mid % col] < target)
start = mid;
else if (matrix[mid / col][mid % col] > target)
end = mid;
}
if(matrix[start / col][start % col] == target)
return true;
if(matrix[end / col][end % col] == target)
return true;
return false;
}
}