Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties:
- Integers in each row are sorted from left to right.
- The first integer of each row is greater than the last integer of the previous row.
For example,
Consider the following matrix:
[
[1, 3, 5, 7],
[10, 11, 16, 20],
[23, 30, 34, 50]
]
Given target = 3, return true.
一刷
題解：
將多維矩陣視為一維
public class Solution {
public boolean searchMatrix(int[][] matrix, int target) {
if(matrix == null || matrix.length == 0) return false;
int n = matrix.length, m = matrix[0].length;
int lo = 0;
int hi = m*n - 1;
while(hi>=lo){
int mid = lo + (hi - lo)/2;
int num = matrix[mid/m][mid%m];
if( num == target) return true;
else if(num < target) lo = mid+1;
else hi = mid-1;
}
return false;
}
}
