import java.util.HashMap;
import java.util.Map;
/**
* 给定一个整数数组 nums 和一个目标值 target，请你在该数组中找出和为目标值的那 两个 整数，并返回他们的数组下标。
* 你可以假设每种输入只会对应一个答案。但是，你不能重复利用这个数组中同样的元素。
* <p>
* 示例:
* 给定 nums = [2, 7, 11, 15], target = 9
* 因为 nums[0] + nums[1] = 2 + 7 = 9
* 所以返回 [0, 1]
* 2019/7/21
*/
public class No1 {
public static void main(String[] args) {
int[] nums = {1, 2, 3, 4, 5
};
int target = 6
;
int[] position =
new No1().solution1(nums, target);
for (
int x : position
) {
System.out.print(x + " "
);
}
}
private int[] solution(
int[] nums,
int target) {
for (
int i = 0; i < nums.length; i++
) {
for (
int j = i + 1; j < nums.length; j++
) {
if ((i != j) && (target - nums[i] ==
nums[j])) {
return new int[]{i, j};
}
}
}
return null;
}
private int[] solution1(
int[] nums,
int target) {
Map<Integer, Integer> numMap =
new HashMap<>
();
for (
int i = 0; i < nums.length; i++
) {
numMap.put(nums[i], i);
}
for (
int j = 0; j < nums.length; j++
) {
if (numMap.containsKey(target - nums[j]) && numMap.get(target - nums[j]) !=
j) {
return new int[]{j, numMap.get(target -
nums[j])};
}
}
return null;
}
private int[] solution2(
int[] nums,
int target) {
Map<Integer, Integer> map =
new HashMap<>
();
for (
int i = 0; i < nums.length; i++
) {
int complement = target -
nums[i];
if (map.containsKey(complement)) {
return new int[]{map.get(complement), i};
}
map.put(nums[i], i);
}
throw new IllegalArgumentException("No two sum solution"
);
}
}
转载于:https://www.cnblogs.com/GG-Bond/p/11220991.html
