Competitive-Programming/Binary Search.cpp at master · idzharbae/Competitive-Programming · GitHub

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int binser(vi arr, int val){
	int l = 0, r = arr.size()-1,mid;
	while(l<=r){
		mid = (l+r)/2;
		if(arr[mid] == val) return mid;
		else if(val > arr[mid]) l = mid+1;
		else r = mid-1;
	}
	return mid;
}

// lower bound (not greater)
int binser(vi arr, int val){
	int l = 0, r = arr.size()-1,mid = (l+r)/2;;
	while(l<r){
		if(arr[mid] == val) return mid;
		else if(val >= arr[mid]) l = mid+1;
		else r = mid-1;
		mid = (l+r)/2;
	}
	if(arr[mid] > val) mid--;
	return mid;
}

//upper bound (greater)
int binser(vi arr, int val){
	int l = 0, r = arr.size()-1,mid = (l+r)/2;;
	while(l<r){
		if(arr[mid] == val) return mid+1;
		else if(val >= arr[mid]) l = mid+1;
		else r = mid-1;
		mid = (l+r)/2;
	}
	if(arr[mid] <= val) mid++;
	return mid;
}

int binser(int l, int r, int val){
	while(r-l > 0){
		int mid = (l+r)/2;

		if(mid >= val)
			r = mid;
		else if(mid == l)
			break;
		l = mid;
	}

	return r;
}