[Algorithm] - Linear search and Binay Search
Tuesday, December 10, 2019
1. Linear search
Time:
- Worst: O(n)
- Average:
- Best:
Code:
public class LinearSearchExample {
private static int[] a = {1000, 11, 50, 1, 2, 3, 78, 100, 101, 102, 1000, 1000};
public static void main(String[] args) {
int x = 1000;
int count = 0;
for (int i = 0; i < a.length; i++) {
if (a[i] == x) {
count++;
}
}
if (count == 0) {
System.out.println("not found");
} else {
System.out.println("Match results: " + count);
}
}
}
2. Binary search
Time:
- Worst:O (log n)
- Average:
- Best:
Code:
public class BinarySearchExample {
// sorted array
private static int[] a = { 10, 21, 23, 54, 61, 72 };
public static void main(String[] args) {
int x = 10;
// sort array
int left = 0;
int right = a.length;
int mid;
while (left <= right) {
mid = (left + right - 1) / 2;
if (a[mid] == x) {
System.out.println("Found " + x + " in array.");
break;
} else if (a[mid] < x) {
left = mid + 1;
} else {
right = mid - 1;
}
}
}
}
Time:
- Worst: O(n)
- Average:
- Best:
Code:
public class LinearSearchExample {
private static int[] a = {1000, 11, 50, 1, 2, 3, 78, 100, 101, 102, 1000, 1000};
public static void main(String[] args) {
int x = 1000;
int count = 0;
for (int i = 0; i < a.length; i++) {
if (a[i] == x) {
count++;
}
}
if (count == 0) {
System.out.println("not found");
} else {
System.out.println("Match results: " + count);
}
}
}
2. Binary search
Time:
- Worst:O (log n)
- Average:
- Best:
Code:
public class BinarySearchExample {
// sorted array
private static int[] a = { 10, 21, 23, 54, 61, 72 };
public static void main(String[] args) {
int x = 10;
// sort array
int left = 0;
int right = a.length;
int mid;
while (left <= right) {
mid = (left + right - 1) / 2;
if (a[mid] == x) {
System.out.println("Found " + x + " in array.");
break;
} else if (a[mid] < x) {
left = mid + 1;
} else {
right = mid - 1;
}
}
}
}
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