How to Prepare for Coding Interviews in 90 Days — Complete Guide

Cracking software engineering interviews requires structured preparation, pattern recognition, and consistent practice.

Standard Template: Two Pointers Pattern

Here is the essential template in all 4 languages:

cpp
int twoSumSorted(vector<int>& nums, int target) {
    int l = 0, r = nums.size() - 1;
    while (l < r) {
        int sum = nums[l] + nums[r];
        if (sum == target) return l;
        else if (sum < target) l++;
        else r--;
    }
    return -1;
}

java
public int twoSumSorted(int[] nums, int target) {
    int l = 0, r = nums.length - 1;
    while (l < r) {
        int sum = nums[l] + nums[r];
        if (sum == target) return l;
        else if (sum < target) l++;
        else r--;
    }
    return -1;
}

python
def twoSumSorted(nums: list, target: int) -> int:
    l, r = 0, len(nums) - 1
    while l < r:
        total = nums[l] + nums[r]
        if total == target: return l
        elif total < target: l += 1
        else: r -= 1
    return -1

javascript
function twoSumSorted(nums, target) {
    let l = 0, r = nums.length - 1;
    while (l < r) {
        let total = nums[l] + nums[r];
        if (total === target) return l;
        else if (total < target) l++;
        else r--;
    }
    return -1;
}

90-Day Execution Plan

• Days 1–30: Arrays, Strings, Two Pointers, Sliding Window, Linked Lists.
• Days 31–60: Stacks, Queues, Binary Trees, Binary Search Trees, Heaps.
• Days 61–90: Graphs, Dynamic Programming, System Design (LLD), Mock Interviews.

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