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SearchA2DMatrixII.java
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83 lines (70 loc) · 2.23 KB
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public class BinarySearchSolution {
public boolean searchMatrix(int[][] matrix, int target) {
boolean result = false;
for (int i = 0; i < matrix.length; i++) {
result |= binarySearch(matrix[i], target);
}
return result;
}
public boolean binarySearch(int[] nums, int target) {
int low = 0;
int high = nums.length - 1;
while (low <= high) {
int mid = low + (high-low) / 2;
if (nums[mid] == target) {
return true;
} else if (nums[mid] > target) {
high = mid - 1;
} else {
low = mid + 1;
}
}
return false;
}
}
public class LinearSolution {
public boolean searchMatrix(int[][] matrix, int target) {
int rows = matrix.length;
if (rows == 0) {
return false;
}
int cols = matrix[0].length - 1;
for (int i = 0; i < rows; i++) {
while (cols > 0 && matrix[i][cols] > target) {
cols -= 1;
}
if (matrix[i][cols] == target) {
return true;
}
}
return false;
}
}
public class DivideAndConquerSolution {
public int[][] matrix;
public int target = 0;
public boolean searchMatrix(int[][] matrix, int target) {
this.matrix = matrix;
this.target = target;
int rows = this.matrix.length;
if (rows == 0) {
return false;
}
int cols = this.matrix[0].length;
return this.eliminateQuarter(0, rows-1, 0, cols-1);
}
public boolean eliminateQuarter(int rs, int re, int cs, int ce) {
if (rs > re || cs > ce) {
return false;
}
int rm = rs + (re-rs) / 2;
int cm = cs + (ce-cs) / 2;
if (this.matrix[rm][cm] == this.target) {
return true;
} else if (this.matrix[rm][cm] < target) {
return eliminateQuarter(rs, rm, cm+1, ce) || eliminateQuarter(rm+1, re, cs, ce);
} else {
return eliminateQuarter(rs, rm-1, cs, ce) || eliminateQuarter(rm, re, cs, cm-1);
}
}
}