XOR Queries of a Subarray
给一个数组和一个queries数组, 让返回一个数组, 是queries中范围的xor值. 这个题就是pre sum.
class Solution {
public int[] xorQueries(int[] arr, int[][] queries) {
for(int i = 1; i < arr.length; i++) {
arr[i] = arr[i] ^ arr[i-1];
}
int[] res = new int[queries.length];
for(int i = 0; i < queries.length; i++) {
if(queries[i][0] > 0)
res[i] = arr[queries[i][1]] ^ arr[queries[i][0]-1];
else
res[i] = arr[queries[i][1]];
}
return res;
}
}