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Copy pathWaterProblem.java
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120 lines (110 loc) · 3.61 KB
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package pointer;
import java.util.HashMap;
import java.util.Map;
/**
* @Author: wei1
* @Date: Create in 2018/11/26 19:01
* @Description: 用两个指针代替了数组的记录功能省空间
*/
public class WaterProblem {
public static int getWater1(int[] arr) {
if (arr == null || arr.length < 3) {
return 0;
}
int value = 0;
for (int i = 1; i < arr.length - 1; i++) {
int leftMax = 0;
int rightMax = 0;
for (int l = 0; l < i; l++) {
leftMax = Math.max(arr[l], leftMax);
}
for (int r = i + 1; r < arr.length; r++) {
rightMax = Math.max(arr[r], rightMax);
}
value += Math.max(0, Math.min(leftMax, rightMax) - arr[i]);
}
return value;
}
public static int getWater2(int[] arr) {
if (arr == null || arr.length < 3) {
return 0;
}
int n = arr.length - 2;
int[] leftMaxs = new int[n];
leftMaxs[0] = arr[0];
for (int i = 1; i < n; i++) {
leftMaxs[i] = Math.max(leftMaxs[i - 1], arr[i]);
}
int[] rightMaxs = new int[n];
rightMaxs[n - 1] = arr[n + 1];
for (int i = n - 2; i >= 0; i--) {
rightMaxs[i] = Math.max(rightMaxs[i + 1], arr[i + 2]);
}
int value = 0;
for (int i = 1; i <= n; i++) {
value += Math.max(0, Math.min(leftMaxs[i - 1], rightMaxs[i - 1]) - arr[i]);
}
return value;
}
public static int getWater3(int[] arr) {
if (arr == null || arr.length < 3) {
return 0;
}
int n = arr.length - 2;
int[] rightMaxs = new int[n];
rightMaxs[n - 1] = arr[n + 1];
for (int i = n - 2; i >= 0; i--) {
rightMaxs[i] = Math.max(rightMaxs[i + 1], arr[i + 2]);
}
int leftMax = arr[0];
int value = 0;
for (int i = 1; i <= n; i++) {
value += Math.max(0, Math.min(leftMax, rightMaxs[i - 1]) - arr[i]);
leftMax = Math.max(leftMax, arr[i]);
}
return value;
}
public static int getWater4(int[] arr) {
if (arr == null || arr.length < 3) {
return 0;
}
int value = 0;
int leftMax = arr[0];
int rightMax = arr[arr.length - 1];
int l = 1;
int r = arr.length - 2;
while (l <= r) {
if (leftMax <= rightMax) {
value += Math.max(0, leftMax - arr[l]);
leftMax = Math.max(leftMax, arr[l++]);
} else {
value += Math.max(0, rightMax - arr[r]);
rightMax = Math.max(rightMax, arr[r--]);
}
}
return value;
}
public static int[] generateRandomArray() {
int[] arr = new int[(int) (Math.random() * 98) + 2];
for (int i = 0; i < arr.length; i++) {
arr[i] = (int) (Math.random() * 200) + 2;
}
return arr;
}
public static void main(String[] args) {
for (int i = 0; i < 1000000; i++) {
int[] arr = generateRandomArray();
int r1 = getWater1(arr);
int r2 = getWater2(arr);
int r3 = getWater3(arr);
int r4 = getWater4(arr);
if (r1 != r2 || r3 != r4 || r1 != r3) {
System.out.println("What a fucking day! fuck that! man!");
}
}
HashMap<String, String> map = new HashMap<String, String>();
for (Map.Entry<String, String> entry : map.entrySet()) {
System.out.println(entry.getKey() + " , " + entry.getValue());
}
}
}