// CSE 143, Winter 2011, Marty Stepp
// This program performs some operations and
// measures and reports the total runtime.
// It forms a basis for runtime efficiency testing.

import java.util.*;

public class SpeedTest {
	public static void main(String[] args) {
		// perform a timing test for arrays of increasing size (doubling every time)
		System.out.println("N\tTime (ms)");
		for (int n = 100; n <= 10000; n = n * 2) {
			timingTest(n);
		}
	}

	// Computes max subsequence sum on a randomly generated array of the given size.
	public static void timingTest(int size) {
		// create an array of random data with a mixture of positive and negative values
		int[] a = new int[size];
		Random rand = new Random();
		for (int i = 0; i < a.length; i++) {
			a[i] = rand.nextInt(1001) - 500;
		}

		// get start/stop system times to find out how fast the code ran
		long startTime = System.currentTimeMillis();
		int sum = maxSum1(a);
		long endTime = System.currentTimeMillis();

		System.out.println(size + "\t" + (endTime - startTime));
	}

	public static int maxSum1(int[] a) {
		int max = 0;
		for (int i = 0; i < a.length; i++) {
			for (int j = i; j < a.length; j++) {
				// sum = add the elements from a[i] to a[j].
				int sum = 0;
				for (int k = i; k <= j; k++) {
					sum += a[k];
				}
				if (sum > max) {
					max = sum;
				}
			}
		}
		return max;
	}


















	public static int maxSum2(int[] a) {
		int max = 0;
		for (int i = 0; i < a.length; i++) {
			int sum = 0;
			for (int j = i; j < a.length; j++) {
				sum += a[j];
				if (sum > max) {
					max = sum;
				}
			}
		}
		return max;
	}















	public static int maxSum3(int[] a) {
		int max = 0;
		int sum = 0;
		int i = 0;
		for (int j = 0; j < a.length; j++) {
			if (sum < 0) {   // if sum becomes negative, max range
				i = j;       // cannot start with any of i - j-1
				sum = 0;     // (Claim 2)
			}
			sum += a[j];
			if (sum > max) {
				max = sum;
			}
		}
		return max;
	}
}