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test45.java
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47 lines (43 loc) · 1.58 KB
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package byteDance;
/**
* Created by lizeyang on 2020/5/16.
* 以log(m+n)的时间复杂度完成矩阵搜索
*/
public class test45 {
//行列均使用二分查找，时间复杂度O(logm+logn)
public static boolean test(int[][] matrix, int target) {
if (matrix == null || matrix.length == 0 || matrix[0].length == 0) {
return false;
}
return search(matrix, 0, matrix.length - 1, 0, matrix[0].length - 1, target);
}
public static boolean search(int[][] matrix, int xStart, int xEnd, int yStart, int yEnd, int target) {
if (xStart > xEnd || yStart > yEnd) {
return false;
}
int index = (xStart + xEnd) >> 1;
int res = binarySearch(matrix[index], yStart, yEnd, target);
if (matrix[index][res] == target) {
return true;
}
return search(matrix, xStart, index - 1, yStart, yEnd, target) || search(matrix, index + 1, xEnd, yStart, yEnd, target);
}
public static int binarySearch(int[] matrix, int l, int r, int target) {
while (l < r) {
int mid = (l + r) >> 1;
if (matrix[mid] == target) {
return mid;
} else if (matrix[mid] < target) {
l = mid + 1;
} else {
r = mid - 1;
}
}
return l;
}
public static void main(String[] args) {
int[][] matrix = {{1, 4, 7, 11, 15}, {2, 5, 8, 12, 19}, {3, 6, 9, 16, 22}, {10, 13, 14, 17, 24}, {18, 21, 23, 26, 30}};
int target = 20;
System.out.println(test(matrix, target));
}
}