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SearchMatrixII240.java
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SearchMatrixII240.java
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package Leetcode;
public class SearchMatrixII240 {
/**Method1: Binary search with iterating on the diagonal; Time: O(lg(min(m,n) !)); Space: O(1) **/
public boolean searchMatrix1(int[][] matrix, int target) {
if(matrix == null || matrix[0] == null) {
return false;
}
int shortLen = Math.min(matrix.length, matrix[0].length);
for(int i=0; i < shortLen; i++) {
boolean colFound = binSearch(matrix, i, target, true);
boolean rowFound = binSearch(matrix, i, target, false);
if(colFound || rowFound) {
return true;
}
}
return false;
}
private boolean binSearch(int[][] matrix, int num, int target, boolean isCol) {
int s = num;
int e = isCol? matrix[0].length-1: matrix.length-1;
while(s <= e) {
int mid = s + (e - s) /2;
if(isCol) {
if(matrix[num][mid] < target) {
s = mid + 1;
} else if(matrix[num][mid] > target) {
e = mid-1;
} else {
return true;
}
} else {
if(matrix[mid][num] < target) {
s = mid + 1;
} else if(matrix[mid][num] > target) {
e = mid -1;
} else {
return true;
}
}
}
return false;
}
/**Method2: Binary search from c=0 and r = row-1; Time: O(m + n); Space: O(1) **/
public boolean searchMatrix(int[][] matrix, int target) {
if(matrix == null || matrix[0] == null) {
return false;
}
int row = matrix.length;
int col = matrix[0].length;
int r = 0;
int c = col - 1;
while(c>=0 && r <row) {
if(matrix[r][c] == target) {
return true;
} else if(matrix[r][c] > target) {
c--;
} else if(matrix[r][c] < target) {
r++;
}
}
return false;
}
}