Reachability / farthest reach (Greedy Sub-pattern)

// nums[i] = longest jump from i. Every index up to far is reachable.
bool canReachEnd(const vector<int>& nums) {
    int far = 0;
    for (int i = 0; i < (int)nums.size(); i++) {
        if (i > far) return false;                           // a gap nobody can jump over
        far = max(far, i + nums[i]);
    }
    return true;
}

// Fewest jumps: indexes reachable with k jumps form one block [.., curEnd] (a BFS level).
int minJumps(const vector<int>& nums) {
    int jumps = 0, curEnd = 0, far = 0;
    for (int i = 0; i + 1 < (int)nums.size(); i++) {
        far = max(far, i + nums[i]);
        if (i == curEnd) { jumps++; curEnd = far; }          // level finished: one more jump
    }
    return jumps;                                            // assumes the end is reachable
}