g0801_0900.s0835_image_overlap.Solution Maven / Gradle / Ivy
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Java Solution for LeetCode algorithm problems, continually updating
package g0801_0900.s0835_image_overlap;
// #Medium #Array #Matrix #2022_03_24_Time_6_ms_(98.73%)_Space_43.4_MB_(60.76%)
public class Solution {
public int largestOverlap(int[][] img1, int[][] img2) {
int[] bits1 = bitwise(img1);
int[] bits2 = bitwise(img2);
int n = img1.length;
int res = 0;
for (int hori = -1 * n + 1; hori < n; hori++) {
for (int veti = -1 * n + 1; veti < n; veti++) {
int curOverLapping = 0;
if (veti < 0) {
for (int i = -1 * veti; i < n; i++) {
if (hori < 0) {
curOverLapping +=
Integer.bitCount(
(bits1[i] << -1 * hori) & bits2[i - -1 * veti]);
} else {
curOverLapping +=
Integer.bitCount((bits1[i] >> hori) & bits2[i - -1 * veti]);
}
}
} else {
for (int i = 0; i < n - veti; i++) {
if (hori < 0) {
curOverLapping +=
Integer.bitCount((bits1[i] << -1 * hori) & bits2[veti + i]);
} else {
curOverLapping +=
Integer.bitCount((bits1[i] >> hori) & bits2[veti + i]);
}
}
}
res = Math.max(res, curOverLapping);
}
}
return res;
}
private int[] bitwise(int[][] img) {
int[] bits = new int[img.length];
for (int i = 0; i < img.length; i++) {
int cur = 0;
for (int j = 0; j < img[0].length; j++) {
cur = cur * 2 + img[i][j];
}
bits[i] = cur;
}
return bits;
}
}