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Java Solution for LeetCode algorithm problems, continually updating
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package g1901_2000.s1901_find_a_peak_element_ii;
// #Medium #Array #Binary_Search #Matrix #Divide_and_Conquer #Binary_Search_II_Day_17
// #2022_05_11_Time_0_ms_(100.00%)_Space_115.1_MB_(45.96%)
public class Solution {
public int[] findPeakGrid(int[][] mat) {
int n = mat.length;
int m = mat[0].length;
int l = 0;
int r = m - 1;
int mid;
while (l <= r) {
mid = (l + r) / 2;
int mx = mat[0][mid];
int mxi = 0;
for (int i = 1; i < n; i++) {
if (mx < mat[i][mid]) {
mx = mat[i][mid];
mxi = i;
}
}
int lv = mid > l ? mat[mxi][mid - 1] : -1;
int rv = mid < r ? mat[mxi][mid + 1] : -1;
if (mx > lv && mx > rv) {
return new int[] {mxi, mid};
} else if (mx > lv) {
l = mid + 1;
} else {
r = mid - 1;
}
}
return new int[] {-1, -1};
}
}