Majority Number II

题目描述

链接地址

解法

算法解释

题目描述

Given an array of integers, the majority number is the number that occurs more than 1/3 of the size of the array.

Example

Given [1, 2, 1, 2, 1, 3, 3], return 1.

Note

There is only one majority number in the array.

Challenge

O(n) time and O(1) extra space.

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链接地址

http://www.lintcode.com/en/problem/majority-number-ii/

解法

int majorityNumber(vector<int> nums){
// write your code here
int num1 = 0, num2 = 0;
int ret1 = 0, ret2 = 0;
for (int i = 0; i < nums.size(); i++) {
if (num1 != 0 && ret1 == nums[i]) {
num1++;
} else if (num2 != 0 && ret2 == nums[i]) {
num2++;
} else if (num1 != 0 && num2 != 0) {
num1--;
num2--;
} else if (num1 == 0) {
num1 = 1;
ret1 = nums[i];
} else {
num2 = 1;
ret2 = nums[i];
}
}
int count1 = 0, count2 = 0;
for (int i = 0; i < nums.size(); i++) {
if (ret1 == nums[i]) {
count1++;
} else if (ret2 == nums[i]) {
count2++;
}
}
if (count1 > count2) {
return ret1;
} else {
return ret2;
}
}

算法解释

正如算法Majority Number，同时删除两个元素，现在同时删除三个元素。