LeetCode OJ-- Search a 2D Matrix
https://oj.leetcode.com/problems/search-a-2d-matrix/
具有数据递增性质的一个二维数组,对它进行二分搜索。
首先搜索target所在的行,再找列。
class Solution {
public:
bool searchMatrix(vector<vector<int> > &matrix, int target) {
if(matrix.size() == )
return false;
size_t col = matrix[].size();
if(col == )
return false;
//first find row
int lowRow = , highRow = matrix.size() - ;
int targetRow = ;
while(lowRow <= highRow && highRow >= && lowRow< matrix.size())
{
int midRow = (lowRow + highRow)/;
if(target < matrix[midRow][])
{
highRow = midRow - ;
if(highRow < )
return false;
}
else if(target == matrix[midRow][] || target == matrix[midRow][col - ])
return true;
else if(col!= && target < matrix[midRow][col - ])
{
targetRow = midRow;
break;
}
else
{
lowRow = midRow + ;
if(lowRow >= matrix.size())
return false;
}
}
//find col binary search
int lowCol = , highCol = col;
while(lowCol <= highCol)
{
int midCol = (lowCol + highCol)/;
if(matrix[targetRow][midCol] == target)
return true;
else if(matrix[targetRow][midCol] < target)
lowCol = midCol + ;
else
highCol = midCol - ;
}
return false;
}
};
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