g1101_1200.s1187_make_array_strictly_increasing.Solution Maven / Gradle / Ivy

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package g1101_1200.s1187_make_array_strictly_increasing;

// #Hard #Array #Dynamic_Programming #Binary_Search
// #2022_03_03_Time_33_ms_(95.51%)_Space_42.4_MB_(82.02%)

import java.util.Arrays;

/**
 * 1187 - Make Array Strictly Increasing\.
 *
 * Hard
 *
 * Given two integer arrays `arr1` and `arr2`, return the minimum number of operations (possibly zero) needed to make `arr1` strictly increasing.
 *
 * In one operation, you can choose two indices `0 <= i < arr1.length` and `0 <= j < arr2.length` and do the assignment `arr1[i] = arr2[j]`.
 *
 * If there is no way to make `arr1` strictly increasing, return `-1`.
 *
 * **Example 1:**
 *
 * **Input:** arr1 = [1,5,3,6,7], arr2 = [1,3,2,4]
 *
 * **Output:** 1
 *
 * **Explanation:** Replace `5` with `2`, then `arr1 = [1, 2, 3, 6, 7]`.
 *
 * **Example 2:**
 *
 * **Input:** arr1 = [1,5,3,6,7], arr2 = [4,3,1]
 *
 * **Output:** 2
 *
 * **Explanation:** Replace `5` with `3` and then replace `3` with `4`. `arr1 = [1, 3, 4, 6, 7]`.
 *
 * **Example 3:**
 *
 * **Input:** arr1 = [1,5,3,6,7], arr2 = [1,6,3,3]
 *
 * **Output:** -1
 *
 * **Explanation:** You can't make `arr1` strictly increasing.
 *
 * **Constraints:**
 *
 * *   `1 <= arr1.length, arr2.length <= 2000`
 * *   `0 <= arr1[i], arr2[i] <= 10^9`
**/
public class Solution {
    public int makeArrayIncreasing(int[] arr1, int[] arr2) {
        Arrays.sort(arr2);
        int start = 0;
        for (int i = 0; i < arr2.length; i++) {
            if (arr2[i] != arr2[start]) {
                arr2[++start] = arr2[i];
            }
        }
        int l2 = start + 1;
        int[] dp = new int[l2 + 2];
        for (int i = 0; i < arr1.length; i++) {
            int noChange = dp[dp.length - 1];
            if (i > 0 && (arr1[i - 1] >= arr1[i])) {
                noChange = -1;
            }
            for (int j = dp.length - 2; j > 0; j--) {
                if (arr2[j - 1] < arr1[i] && dp[j] != -1) {
                    noChange = noChange == -1 ? dp[j] : Math.min(noChange, dp[j]);
                }
                if (dp[j - 1] != -1) {
                    dp[j] = 1 + dp[j - 1];
                } else {
                    dp[j] = -1;
                }
                if (i > 0 && arr1[i - 1] < arr2[j - 1] && dp[dp.length - 1] >= 0) {
                    dp[j] =
                            dp[j] == -1
                                    ? (dp[dp.length - 1] + 1)
                                    : Math.min(dp[j], dp[dp.length - 1] + 1);
                }
            }
            dp[0] = -1;
            dp[dp.length - 1] = noChange;
        }
        int res = -1;
        for (int num : dp) {
            if (num != -1) {
                res = res == -1 ? num : Math.min(res, num);
            }
        }
        return res;
    }
}